Chevy C10 Gas Tank Relocation Guide

Last Updated April 16, 2024 | Cory Jones

The Chevy C10 is respected as a classic American truck in the eyes of many enthusiasts. Despite the fondness for this truck from the auto community, the original C10 models came with quite a few safety issues by modern standards.

One of the most crucial safety problems for the C10 is the location of the gas tank. Original C10 models had the fuel tank located in the cab with the driver. This placement made it much more likely for the driver to be exposed to gas fumes as well as making the cabin more susceptible to catching on fire in the event of a crash.

The best solution to this problem is to relocate the gas tank from inside the cabin to below the bed, between the frame rails. A Chevy C10 gas tank relocation will drastically improve the safety of your classic truck for daily driving.

This installation will require some slight frame modifications, but don't worry. We offer detailed instructions for each step of the process as well as the tools and tips to get the job done right. Following the outline below, you'll be able to relocate your C10's gas tank and install a new fuel filler neck within a day's work.

Removing The C10 Bed

You'll need to remove your C10's bed to relocate the gas tank. Follow the steps in the video below in order to remove your C10's bed and continue with the relocation.

Part 1: Chevy C10 Gas Tank Relocation Steps

We're using the popular C10 fuel tank conversion kit for this installation. This kit is designed to fit 1969, 1970, 1971, And 1972 Chevy C10s And GMC Trucks.

Parts and Tools Needed:

Step 1: Remove the Seats

Use a wrench to unscrew the bolts holding the seats in place. Begin by unscrewing the bolts at the base of the seat. Next, head underneath the truck to unscrew the nuts on the bottom of the frame. Once the bolts are removed, pull the seat bench out of the cabin through the driver's side door.

Step 2: Remove Seat Belts and Pull Back Carpet

Remove the bolts at the base of the seat belts in the center of the cab. Next, remove the top shoulder bolts as well as the bolts at the base of the seat belt feed assembly on either side of the cab. With these bolts removed, pull back the carpet slightly to access the stock filler tank.

Step 3: Remove Soft Fuel Line

Head underneath your C10 and find the soft fuel line coming out of the bottom of the stock fuel tank. Use a screwdriver to remove the small screw on the hose clamp connecting the hard fuel line to the soft fuel line. Once the attachment is loose, slide the soft line away from the hard line until they are disconnected.

Step 4: Pull Hard Line Through Truck Cab

Head back to the cabin and disconnect the hard line from the tank. Pull the bottom of the line towards the cabin to remove it from the assembly.

Step 5: Remove Gas Tank

Before removing the bolts, disconnect the sending unit wire in the center of the tank near the cap. With the wire removed, unscrew the remaining bolts holding the tank in place. Then, remove the tank from the cabin.

Step 6: Mock Up Gas Tank Position

If you haven't already removed your C10's bed, check out the video at the top of these steps to get that done before you continue.

Head to the back of the truck and place your new fuel tank on the ground beneath the second to last divided section of the frame rails. Once the tank is stable, use a jack to raise it into position. The tank should be positioned so it is resting against the rear cross support.

Pro Tip: Your C10 may have an additional cross support in the way of the new gas tank location. It is typically there to store the spare tire. If this is the case, detach this support by removing the rivets holding the cross support in position before completing this step.

Step 7: Cut Hole For Filler Neck

With the new tank in position, determine the location of the new filler arm. Use a marker to draw a 2.5” semi-circle around the area where the new filler arm will rest. Use a 2.5” hole saw to create an initial divot in the frame rail. Lubricate the area, then press down with the saw to cut out the marked off section of the frame rail.

Step 8: Clean Up the Metal Edges

Using a grindsaw, cut off the rough edges of the removed area of the frame rail. Grind down the sides of the sliced section until the metal is smooth, with no sharp edges. There may be some bare metal exposed once the area is cleaned up.. Add some paint to the exposed metal, to keep it from rusting.

Step 9: Mock Up Gas Tank Straps

Head underneath the new gas tank and place the gas tank straps on either side. Mark the location for the holes to be drilled on the frame rail with a marker.

Step 10: Drill Holes for Gas Tank on Driver's Side

Use a ⅜” drill bit to drill a hole in the areas you marked in the last step.

Step 11: Mount New Gas Tank Driver's Side

The gas tank relocation kit comes with the j-hooks needed for mounting the tank on the passenger's side. However, you'll need to provide the mounting hardware for the driver's side. Slide a bolt through the drilled hole and install a nut on the bottom to hold it in place, then tighten it down. Repeat this process for all mounting points on the driver's side.

Step 12: Drill Passenger's Side Mounting Holes

Grab the j-hook included with your kit and put a dot of paint on the end. Slide the j-hook through the hole in the gas tank strap on the passenger's side. Raise the assembly until it touches the frame rail. The paint from the j-hook will let you know where to drill the hole in the frame rail. Use a ⅜” drill bit to drill a hole in the painted area following the same process as step 10.

Step 13: Mount Tank on Passenger's Side

Attach the j-hooks to the gas tank straps and slide the hooks through the drilled holes. Use the included nuts to hold the hooks in place on the top side of the frame rail. Then, tighten down the nuts.

Step 14: Insert Sending Unit

First, grab the gasket for the sending unit housing and install it around the hole. Next, insert the sending unit into the hole, allowing it to rest on the gasket. Finally, install the locking ring around the top of the sending unit and lock it in place by turning it clockwise.

Pro Tip: You can use a screwdriver to push the locking ring in a clockwise direction. Make sure each of the three locking ring tabs are connected underneath the ring.

Step 15: Attach Grounding Wire to Frame

Insert the provided bolt into a hole on the frame rail. Take the grounding wire from the sending unit and attach it at the bottom of the bolt. Then, screw the provided nut onto the bolt beneath the grounding wire and tighten the assembly.

Step 16: Run New Soft Line Along Frame Rail

Attach the new soft line to the sending unit with a hose clamp. Run the line along the frame rail and zip tie it at each crossmember to make sure it's secure. Feed the hose through the frame at the base of the cab.

Pro Tip: If you're having problems with the hose rubbing up against raw metal, slice off a section of hose and cut down the center to make a buffer you can attach to the frame rail.

Step 17: Attach New Soft Line to Factory Fuel Hard Line

Disconnect the old soft line from the factory hard line. Slide the new line on so it is securely attached, then add a hose clamp and tighten it down with a screwdriver.

Step 18: Connect New Sending Unit Wire to Engine

Attach a wire connector to the coolant temperature sensor on your C10's engine. Make sure the attached wire is long enough to reach the sending unit beneath the bed. Take the wire and feed it underneath the truck next to the frame rail.

Step 19: Connect Wiring to New Sending Unit

Take the sending unit wire from the previous step and run it along the frame rail to the new sending unit. Cut the wire to the necessary length and strip the end. Add a wire connector to the exposed wire and crimp the connector to secure it. Unscrew the small nut on top of the sending unit bolt. Attach the wire connector and rethread the nut on top and tighten it.

Pro Tip: Make sure all of your wiring is securely connected to the frame rail with zip ties.

Step 20: Install Breather Hose

Grab a section of gas line and attach a filter at the end using a hose clamp. Feed the hose through the frame rail and connect it to the tank with another hose clamp. Make sure the hose and filter are secured to the frame rail. Use the same process to connect a hose for the filler neck and tighten down the hose clamp on the other side of the tank.

Step 21: Measure Out Frame Rail Cuts

Use a tape measure to mark out the distance between the frame rails where your new gas tank is located. Take those measurements and mark the same distance on the bed frame. Add a few extra inches to be safe.

Step 22: Cut Bed Frame

Use a grind saw to cut into the bed frame at the marked locations from the previous step. Cut about a quarter inch into the frame to make sure it will fit over the gas tank.

Pro Tip: You might not get a clean cut if your C10's bed has rust problems. Make sure to clean up any loose metal that could puncture or damage the tank once you finish cutting.

Part 2: Installing a New Chevy C10 Filler Neck

Follow the steps below to learn how to relocate the filler neck for your new C10 gas tank. We'll be using a fuel filler neck, fuel hose, and fuel filler neck seal for this section of the install.

Step 23: Reinstall C10 Bed

You might need some friends to help you with this step. Lift the truck bed over the frame and let it rest back on the frame rails. Head underneath the bed and reinstall the bolts on either side to secure it to the frame.

Step 24: Mark Out Filler Neck Location

On the top of the bed, decide where you want your new filler neck to go. Then, head underneath the frame and use a marker to trace around the filler neck hose in the location you picked out.

Step 25: Cut Hole for Filler Neck

From underneath the bed drill a small hole through the center of the marked area. Place a small plastic bag over the tip of the filler neck hose to make sure no debris gets into the hose. Head to the top of the bed and use the drilled hole as a centering point for a 2” hole saw. Drill a hole around the center through the bed. Be sure to clean up any bare metal debris with a grind saw.

Step 26: Connect Filler Neck to Hose

Pull the fuel hose through the hole in the bed. Then, grab the filler neck and push it into the fuel hose. Secure the filler neck to the fuel hose with a hose clamp. If your filler neck is not sitting entirely flush with the truck bed, adding a rubber grommet between the neck and the bed can help create a more smooth connection.

Pro Tip: Sometimes the fuel hose is cut too long and creates a kink. Slicing off an inch or two of a longer hose can help fix this problem and allow gas to flow to your new tank more consistently.

Step 27: Install Filler Neck Hardware

Use a screwdriver to install the screws included with the filler neck kit at the three mounting points. Tighten down the screws so the filler neck is flush with the bed.

Congratulations, you're all done!

Make Your C10 Safer with a Gas Tank Relocation

Relocating the gas tank in your classic C10 is an essential update for modern daily driving. With your C10 fuel tank relocation complete, your cabin will be free from lingering gas fumes and potentially dangerous ignition sources. You'll also have more room for storage.

A gas tank relocation is not the only important safety upgrade to modernize your classic C10 truck. There are plenty more essential updates to make your C10 safer like upgrading the brake system, installing LED headlights, and adding 3-point seat belts, just to name a few. Check out our C10 parts page for all the tools you need to add modern safety standards to your C10. Also be sure to visit our Chevy C10 safety upgrades guide for even more modification suggestions.