Hey, I hope this is not covered elsewhere, it must have been but I cannot find it. I am rebuilding a 1951 Canadian 9434 which I believe is the 3/4 ton. I am in the process of replacing the rear suspension pins and the springs are away for refurbishment. The rear is a very low ratio 5.12:1 or thereabouts. I understand that this is the Eaton rear axle HO70 I think and that later 67-72 3/4 ton chev truck 4.1:1 differential will fit right in there, the coil spring auto version apparently. I have read somewhere that the same axle is fitted to fords of the same era.
I'm wanting to keep the same axle but raise the ratio. I'm in the UK and have no issue ordering from USA but would really like some specific info to allow me to use Rock Auto or some other supplier to get all the parts I need to make the change, I would love to get the whole snout assembly to make the swap easier too. I will try and attach some images of the differential.
I'd really appreciate some help on this or pointing in the right direction.
Hy FusionFanatic, welcome, your truck is actually considered a one ton, with a GVW of 8800 lbs.. You are correct about the ability to swap complete differentials with lower (numerically) ratios from newer trucks with automatic transmissions. As far as I am aware there are no "kits" available containing all the bearings and seals required to overhaul the differential and I don't think the crown and pinion are available new. Good luck in your quest, please keep us in the loop on your progress.
Hy FusionFanatic, welcome, your truck is actually considered a one ton, with a GVW of 8800 lbs.. You are correct about the ability to swap complete differentials with lower (numerically) ratios from newer trucks with automatic transmissions. As far as I am aware there are no "kits" available containing all the bearings and seals required to overhaul the differential and I don't think the crown and pinion are available new. Good luck in your quest, please keep us in the loop on your progress.
I have had this truck for 2 years and been calling it a 3/4 the whole time! good job its not that different when ordering parts! Thanks.
Be careful ordering parts designated for a 3/4 ton. The one tons are sometimes very unique beasts and 3/4 ton parts listed saying “fits 1 ton also” may be downright incorrect. For example, brake drums. If you got some that are decent, consider yourself lucky. I bought a junk 1 ton just for the drums on it.
I did this gear swap in my Canadian 51 GMC 1 ton 9434 and it is great. Yes, it is as simple as bolting it in. GM is like LEGO! The hard part is finding that gear set. Rock auto isn’t going to have the complete gear set. You’re looking for a wrecker or parts truck.
Last edited by Fox; 06/23/20225:42 AM.
1970 Chevrolet C10 Grandpa's -- My first truck -- In progress to shiny Follow the build in the Project Journal 1950 Chevrolet 1-Ton Dually "Ole Red Girl" In the Stovebolt Gallery More pictures here 1951 GMC 9430 1 ton dually--Shiny! | 1972 Chevrolet C20- Rusty- the puzzle box lid for the C10 | 1962 AMC Rambler American- my wife's Parts trucks- 1951 GMC 9300 | 1951-GMC 9430 | 1951- Chevrolet 1300
Be careful ordering parts designated for a 3/4 ton. The one tons are sometimes very unique beasts and 3/4 ton parts listed saying “fits 1 ton also” may be downright incorrect. For example, brake drums. If you got some that are decent, consider yourself lucky. I bought a junk 1 ton just for the drums on it.
I did this gear swap in my Canadian 51 GMC 1 ton 9434 and it is great. Yes, it is as simple as bolting it in. GM is like LEGO! The hard part is finding that gear set. Rock auto isn’t going to have the complete gear set. You’re looking for a wrecker or parts truck.
Well I really appreciate that link, I will have a proper read through when I have a bit more time. It is very difficult to be sourcing these parts as donor parts here in the UK. I do have a good friend in Canada who will help me with shipping. At the moment I am concentrating on the rest of the build and I am in the process of changing my workshop location also. I did have all my springs re conditioned and collected those last week, the brakes are in excellent condition and I will only be swapping the slave cylinders which I already have. Not even going to try and use the old ones.
