List of rears

[Smokejohnson]

Hey guys Im looking for a rear end and tranny for my 51 GMC im building. Im looking for a list of cars or trucks with 9" or 12 bolt rears. Also a list of 700R trannys.

[tll74]

The TH700R4 was introduced in 83 and ran thru 92. It was used in light duty trucks, vans, full size pass, camaro, and corvette. As I understand it they progressively got better. My trany guy says the 89-91 is the best choice. The 89-up tranys will have electronic speedo but this is changeable.

For your rearend what is your width (wheel flange to wheel flange) of the original? Do you want to keep it 6 lug? What ratio do you want?

[Smokejohnson]

I don't know the flange to flange width off hand (it's out at my parents place)but I do know the frame is 44" wide. Im using a must ll front end with Chevy bolt pattern so would like the rear to match. I want to put the fattest tire I can under it. I was thinking of tubbing it but I think thats a little over my head. As for ratio I was thinking maybe 373 with posi.

[GMC70c20]

ford put 9ins it every half ton truck I Think form the late 60's to late 80's as far as a 12 bolt they were made from 64-72 and put in passenger cars and ss models and I think some other gm models.

[tll74]

Will this be a daily driver or a weekend warrior? Power plant? I'll find out the width of what you have and do some comparing. Update tommorow

[tll74]

OK.......so heres a list of rearends and their widths.

51-69 pu's........................................................61 1/8
70-87 pu's........................................................63 3/4
65-67 chevelle 67-69 camaro,and 68-79 nova.........59 1/4
68-72 chevelle and 70-81 camaro.........................61 5/16
The cars had 12 bolts and 10 bolts, although the 12 bolts ended in 72.
Hope this helps.

[Smokejohnson]

Thanks for the info. It's going to be a toy or weekend warrior. Im thinkin of puting a 383 stroker in it or some sort of sbc.

[pmpski_1]

Originally Posted by tll74

OK.......so heres a list of rearends and their widths.

51-69 pu's........................................................61 1/8
70-87 pu's........................................................63 3/4
65-67 chevelle 67-69 camaro,and 68-79 nova.........59 1/4
68-72 chevelle and 70-81 camaro.........................61 5/16
The cars had 12 bolts and 10 bolts, although the 12 bolts ended in 72.
Hope this helps.

Not to hijack the original thread, but I'm wondering about the 70-87 specs. I want to get a rear end with 3.08's or near that for my 71 3/4 ton. I'm really hoping to keep the 8-lug axles. If I find a rear with these specs from a 73-87, should it bolt right into my 71? (Of course I'll measure 2x and pay once, but it'll be easier to narrow my search if I know what is compatible)

[Captainfab]

Originally Posted by pmpski_1

Not to hijack the original thread, but I'm wondering about the 70-87 specs. I want to get a rear end with 3.08's or near that for my 71 3/4 ton. I'm really hoping to keep the 8-lug axles. If I find a rear with these specs from a 73-87, should it bolt right into my 71? (Of course I'll measure 2x and pay once, but it'll be easier to narrow my search if I know what is compatible)

It depends on what type of rear suspension you have....coils or leafs. The last year for the coil spring option was '72. So starting in '73 all the trucks had leaf springs in the rear

[pmpski_1]

Leaf, heavy duty according to the SPID in the glove box. Hope that makes it easy...

[tll74]

These spec's are for the the 1/2T rear ends only. The 3/4t's are 65" wide up to 72 and from 73-on they were 67". If you have a D60 you could change it to 3.07 or 3.33. These gears were never used in these trucks and are no longer available new but are available used, although very hard to find. If you have the drop out 1/3 member type then to get a higher ratio you must change out the whole assy. The D60 out of 71-72 would a good choice if you change the ratio, just bolt it in. If you use the 73-up then your highest ratio would be 3.21. These again are hard to find but do exist. I have two of them. The 73-up will require changing the spring pads due to the different spring center to center width and the shock mounts as well. Remeber they are 2" wider overall. I have sold and seen hundreds of these 73-up's in 72-down trucks. So the 2" difference must not be to big of deal.

[pmpski_1]

Originally Posted by tll74

The 73-up will require changing the spring pads due to the different spring center to center width and the shock mounts as well. Remeber they are 2" wider overall. I have sold and seen hundreds of these 73-up's in 72-down trucks. So the 2" difference must not be to big of deal.

Interesting. Thanks for the detailed response. This is exactly what I was looking for. I wouldn't mind the extra width - I always thought the current wheels and tires could fill out the wheel wells a bit more.

Spring pads and shock mounts - changing these on the rear end or on the frame of the truck? Cutting and welding required?

I could compromise on a lower gear ratio if I knew that it would be simple to swap. Simple meaning that I don't have to buy a rebuild kit and learn how to use it

[tll74]

You must change them on the rearend housing and yes cutting and welding is required. A simple job for fabrication guy. The most common ratio for the 73-up 14 bolt will be 3.73 and 4.10.

[Smokejohnson]

Hey guys I can get my hands on a rear from a explorer with disk brakes,posi,and 3.73 gears. Anybody use one of these in there truck?