1968 C50 rear axle swap

[Campbel45]

Has anyone done a rear axle swap on a C50? From what I've seen in forum comments, swapping rear axles between different medium duty models/trucks is fairly straightforward with the exception of moving spring pads and shock mounts. Is overall width pretty standard on these bigger trucks?

I'm hoping I could find a C4500 or something similar with gear ratio near 4.10 - 4.56 and disc brakes.

[Campbel45]

Does anyone know the the rear axle width for these trucks? I'd appreciate the help.

[Campbel45]

I found that the c4500 and c5500 rear axle ratings might be a little low compared to the original axle.

the c6500 can come with an Eaton 19050 or 19060 series axle. I'm not sure what vehicles to look for that have a more heavier duty axle while still retaining hydraulic disc brakes. I would assume as you look for more heavier duty axles you eventually find yourself only looking at air brakes.

Still looking for '68 C50 rear end hub-to-hub width

[richard2717]

Not sure if it help you but my 2000 chevy 6500 has disc breaks on the rear. may be something to consider looking at as well if you still need the weight capacity

[jumpsoffrock]

My '67 C50 rear end differential was swapped out with a higher geared unit. It came with J15 : 20000-LB. 2 SPEED AXLE 6.5/8.58 RATIO

I bought a lighter duty J13 : 15000-LB. 2 SPEED AXLE 4.86/6.61 RATIO

And installed that diff, with 22.5 tubless tires and the new higher geared diff, it is effectively like a 3.73:1 in a normal car, fairly reasonable.

[Campbel45]

jumpsoffrock,

What trans do you have? Do you find yourself needing to use 1st gear more?

I'm having a hard time finding an eaton rear axle near me with everything I'm looking for. I've now turned to looking at International trucks. International has a rear axle, N175, that I've found that comes with rear hydraulic disc, rated for 17,500 lbs, and most have 4.10 ratios. I've found most of these in international 4700 models.

It's not a two speed rear diff but I think a single will do just fine

[jumpsoffrock]

I have an SM420 4-spd Muncie. First gear is granny and is useless for real driving, but great for moving any damn thing you want.


Please keep in mind if you are going to be running truck-size tires(like my 22.5") that this will impact the gear ratio. 4.10:1 ratios will be quite high with such larg diameter tires and your engine may bog in the high gears with big loads.

It really depends what you're doing with the truck. If you are looking at making a 50 year old medium duty truck cruise at 80mph, I learned the hard way that that outlook is not reasonable.

[Pvmt-Pndr]

Man I keep forgetting to measure my rear axle for you! I've been all over the truck for the past week and every day before I mess with it I tell myself to measure the dang axle!
I commented on your other post in the other forum. I have a 17221 with daytons.

[71'tahoe]

I have been looking at late 90's to early 2000's GM Top Kick & Kodiak 6500 trucks. As a matter of fact I went and looked at 24' GM Top Kick today. It has disc brakes front and rear,Hydroboost brake system,Allison transmission with Park,and a big block vortec engine. It too has the tubeless 22.5" wheels. The frame widths are 34" like my 67' C50. Like you I also looked at an international 4700 series,But this one had air brakes but the frame and axle width were what I needed. I mainly looked at the international because it had rear air ride.

[Pvmt-Pndr]

It sounds like a body swap would be the easiest route if you wanted to go that far. I'm still up in the air on an engine swap or not. My little 427 seems to have some decent power left in her for now.

[Campbel45]

Thanks for the replies guys. Is 34” wide frames standard on all big trucks?

[71'tahoe]

Originally Posted by Campbel45

Thanks for the replies guys. Is 34” wide frames standard on all big trucks?

Yes Sir.