1968 C10 Fleet side long bed rear axle to bed measurement

[Jbrem010]

Hey all, the previous owner heated the rear springs on my 1968 C10 and I've added 20" wheels, low sidewall tires and want to lower the rear of the truck. Since nothing is stock, what was original rear axle to bed dimension? This should allow me to determine which drop spring I should go with. I recently installed a 2.5" drop spindle with 2" drop springs on the front and I cut a ring off to drop it another inch (see attached). Thanking you all in advance.

[Jbrem010]

Hey all, I know you all are busy and I recall reading these measurements but I cant find them now. Can I get someone with a stock '68 C10 suspension to measure the distance between the rear axle and the bed or bed cross members? I recognize there may be a little sag after 54 years. Thank you all in advance.

[CC69Rat]

Just trying to help you, most trucks with a 4.5" drop up front will usually run 5-6" drop springs in the rear. It just really depends on how low you want it. But just remember anything over a 4" drop in the rear you will want to relocate your rear shock mounts or it will ride like a train car.

I would suggest buying a 4" spring then a fine tuned adjustment adding a block to your liking. It will ride a lot better with a 4" spring and a 2" block, than it would a 6" drop spring for example.

Think about it like this. If I have a diving board, 12ft long. 250lb man jumps off the end, bounces and into the water. Now, same board, same man. Cut two ft off the board. Does it flex more or less? The same concept works for a drop spring. It's just torsional rigidity. A longer spring will ride like the longer diving board. Where a shorter one will be stiffer like the shorter diving board.

But I'd do 4" spring, 1, 1.5, or 2" drop blocks to adjust from there. Just my .02. Good luck with it man.

[Jbrem010]

Thank you CC69RAT, I think I'll go with the 5" drop and see what blocks I need to add to get me to the right height. I understand I'll probably have to relocate the shock mounts and maybe even a C-notch.

[CC69Rat]

If you have a wood bed floor, the axle center section will be pretty close to the bed floor at 6" drop. It is OK as long as you don't plan to haul a lot in the bed, but just something else to watch out for. The metal bed floor will give you 3/4" more space. 4.5/6 looks good on these trucks.

[lolife99]

Don’t forget a good QUALITY set of drop shocks.
Belltech, Bilstein, Qa1, etc.
(Belltech Street Performance shocks are an affordable shock)
An adjustable panhard bar will be needed to re-center the rear axle in the frame.
The longest panhard bar provides the least amount of side to side movement as the suspension moves.
I suggest one that attaches to the passenger side trailing arm.

[Jbrem010]

Thanks for the recommendations guys! This is coming together.