The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 47-55.1 1951 GMC Floor High Hump

leegreen · 03-10-2023, 01:33 PM

Hi CFF, nice to see another local on the forum.

There are a bunch of ways to fit a newer rearend. if memory recalls swapping to the '64 springs is one of them as the length is similar - but check the width at the eyes too.
You should be able to re-use the 51 springs if you take the spring packs apart, take the top two leafs, and reverse them front to back. Or do the adapter thing dsraven describes.

I assume you want to ditch the 3 speed and closed drive to get higher gears, as already suggested make sure the rear end ratio on that '64 is one that gets you what you want. Any GMC rear axle from a half ton up to like '68-69 should be the right width.

The '64 trans will most likely drive like a 3 speed but with a granny low you will never use. And 1:1 final drive.
I think the '64 292 and bellhousing should be easy bolt up to the '51 clutch linkage but I have not done this myself. The 292 is longer than 216/235, you may need to look for shorter waterpump or switch to electric rad fan. Since you are going to be fabbing engine and trans mounts I'd put the engine and trans in and get it all in place and radiator clearance sorted before worrying too much about the trans hump. You should not need much of a hump

For overdrive options, the t5 will work. Look for lugnutz web page on t5 swaps. I have a '93 s10 t5 behind a 250 in my '52, it is pretty easy. you will need an adapter from smaller trans centre bore to truck bellhousing that is also a spacer to deal with the input shaft length. hotrodworks is where I went and it works perfectly. And a safari van 11" clutch disk. But the 64 bell, PP, release bearing should all be OK. The cost of this can add up, T5s are going for a lot more than they used to, the adapter and clutch disk come from the states and are expensiveish once you get them across the 49.
A NV3500 is also an option and I think you can do that with just a different clutch disk. Nv3500 is a stronger trans but in my experience drives more like a truck trans, the t5 is nicer shifting. Either is strong enough for the 292 or a small v8.

03-10-2023, 01:33 PM	#12
leegreen Registered User Join Date: Mar 2022 Location: Surrey BC Posts: 961	Re: 1951 GMC Floor High Hump Hi CFF, nice to see another local on the forum. There are a bunch of ways to fit a newer rearend. if memory recalls swapping to the '64 springs is one of them as the length is similar - but check the width at the eyes too. You should be able to re-use the 51 springs if you take the spring packs apart, take the top two leafs, and reverse them front to back. Or do the adapter thing dsraven describes. I assume you want to ditch the 3 speed and closed drive to get higher gears, as already suggested make sure the rear end ratio on that '64 is one that gets you what you want. Any GMC rear axle from a half ton up to like '68-69 should be the right width. The '64 trans will most likely drive like a 3 speed but with a granny low you will never use. And 1:1 final drive. I think the '64 292 and bellhousing should be easy bolt up to the '51 clutch linkage but I have not done this myself. The 292 is longer than 216/235, you may need to look for shorter waterpump or switch to electric rad fan. Since you are going to be fabbing engine and trans mounts I'd put the engine and trans in and get it all in place and radiator clearance sorted before worrying too much about the trans hump. You should not need much of a hump For overdrive options, the t5 will work. Look for lugnutz web page on t5 swaps. I have a '93 s10 t5 behind a 250 in my '52, it is pretty easy. you will need an adapter from smaller trans centre bore to truck bellhousing that is also a spacer to deal with the input shaft length. hotrodworks is where I went and it works perfectly. And a safari van 11" clutch disk. But the 64 bell, PP, release bearing should all be OK. The cost of this can add up, T5s are going for a lot more than they used to, the adapter and clutch disk come from the states and are expensiveish once you get them across the 49. A NV3500 is also an option and I think you can do that with just a different clutch disk. Nv3500 is a stronger trans but in my experience drives more like a truck trans, the t5 is nicer shifting. Either is strong enough for the 292 or a small v8.