auto tranny options - The 1947 - Present Chevrolet & GMC Truck Message Board Network

northeastblazer · 04-13-2003, 07:17 PM

What automatic transmissions can be put in a 67-72 in place of the TH350? A list of them would help me a lot so that I can do searches on them. Thanks.

jmanz69 · 04-13-2003, 07:32 PM

From what I understand, if you have the time you can put in any GM transmission. 350, 400, 700R4, 4L60E, 4L80E, it's up to you.
None of the others besides the 400 will go in without much fighting. Even with a 400 you will have to shorten your driveshaft. Are you looking for overdrive, or is your 350 shot? I had a 350 in my 69 and it ran great, had a 300+ HP 327 in front of it and never had a problem. There should be lots of threads about what transmissions go in these trucks and how to do the swap. I see posts about it all the time. Use the search function and see what comes up.

good luck

Rons71 · 04-13-2003, 10:03 PM

Will a 400 trans fit into the low hump cabs?

Eddie H. · 04-13-2003, 10:12 PM

My 69 came factory with a low hump and a 400 tranny.
You can use any of the previously mentioned trannys as well as
a 200 4R which is another overdrive choice that is available.

*rage'nrat638* · 04-13-2003, 10:48 PM

400 is the strongest...with the least amount of work ,,make sure you get one from a truck with the heavy cast case....

heres mine with the jw ultra bell housing installed ,trans brake,h.d output shaft

northeastblazer · 04-13-2003, 10:50 PM

Thanks for the replies guys. I would like overdrive at some point (I don't even have one of these trucks yet, so it's a ways off). Also, besides all of the GM auto transmissions available, are there any aftermarket units worth looking at? Richmond or something like that?

Rons71 · 04-13-2003, 10:52 PM

Do the 400 have a long tailshaft?

*rage'nrat638* · 04-13-2003, 10:56 PM

mine from the 79 c-20 had a short tail shaft and a bolt on yoke
they make a aftermarket yoke if you want it to slip on and off..the worst thing is,,,you may have to get a shiney new drive shaft...or front shaftif you have a two piece?

Rons71 · 04-13-2003, 11:14 PM

I've got the short shaft on my 350 and want to run a 1 piece driveshaft. The driveshaft length is 71" so by going with a long tailshaft and a beefier trans I should be able to run a 68" or so(I think)?

Longhorn Man · 04-13-2003, 11:32 PM

The TH400 came in 3 lengths, the ones under the caddys are the real long ones, I think the med length 400s came in the 73 and up trucks, but I may be mistaken.

jmanz69 · 04-14-2003, 06:53 AM

400's are great if you have a ton of HP and torque. If you are running a mild small block, you will be actually losing HP. It takes 15 or so more HP to turn a 400. So you would need a built small block to make it worth it. I mean like 400 HP or more. A 350 can handle 400 HP if built right. Plus they are cheaper and easier to find.

As far as other trans options, if you want to go with a stick, almost any GM manual will fit. They of course, take a bit of customization to get them in and you will need a new drive shaft. The Muncoe 4 spds, Borg Warner 4 and 5 spds, Richmond 4, 5, and 6 spds all will go in. I am goin with a saginaw car 4 spd. It's not as strong as a Muncie, but I can buy 3 of them for what I can get a muncie for. It will handle my 327 no problem.

vfrdude · 04-14-2003, 05:13 PM

I've got a TH400 in mine, with a 350 and it works fine. The motor has no problems getting the truck moving. It even has 3.08 gears, and the thing will spin the rear wheel (no posi) all the way thru first, then a good ways into second gear. Real easy to chirp the tires going from 1st-2nd.

jmanz69 · 04-14-2003, 09:23 PM

I'm not saying 400's are bad, just not necessary in most cases. The internals of a 400 take more uumf to trun. A 350 is easier for your engine to spin. 400's are the best if you have tons of power, or are towing though. Darn near indestructable. But pricey to buy and rebuild.

04-13-2003, 07:17 PM	#1
northeastblazer Registered User Join Date: Apr 2003 Location: Princeton, NJ and Newton, MA Posts: 22	auto tranny options What automatic transmissions can be put in a 67-72 in place of the TH350? A list of them would help me a lot so that I can do searches on them. Thanks. __________________ Looking for a 69-72 Blazer...

04-13-2003, 10:12 PM	#4
Eddie H. Registered User Join Date: Mar 2001 Location: Paradise TX USA Posts: 1,200	My 69 came factory with a low hump and a 400 tranny. You can use any of the previously mentioned trannys as well as a 200 4R which is another overdrive choice that is available. __________________ "Negative people always seem to have a problem for every solution"

04-13-2003, 10:48 PM	#5
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	400 is the strongest...with the least amount of work ,,make sure you get one from a truck with the heavy cast case.... heres mine with the jw ultra bell housing installed ,trans brake,h.d output shaft Last edited by rage'nrat638; 04-13-2003 at 10:51 PM.

04-13-2003, 10:50 PM	#6
northeastblazer Registered User Join Date: Apr 2003 Location: Princeton, NJ and Newton, MA Posts: 22	Thanks for the replies guys. I would like overdrive at some point (I don't even have one of these trucks yet, so it's a ways off). Also, besides all of the GM auto transmissions available, are there any aftermarket units worth looking at? Richmond or something like that? __________________ Looking for a 69-72 Blazer...

04-14-2003, 05:13 PM	#12
vfrdude Registered User Join Date: May 2002 Location: Oakley, Ca. USA Posts: 137	I've got a TH400 in mine, with a 350 and it works fine. The motor has no problems getting the truck moving. It even has 3.08 gears, and the thing will spin the rear wheel (no posi) all the way thru first, then a good ways into second gear. Real easy to chirp the tires going from 1st-2nd. __________________ Rudy Fierros '95 Honda VFR750F Used to have a '71 Chevy Stepside, Guards Red, Lowered 4" rear, 3" front, White Oak bed wood, 700R4 w/373 gears until some low life stole it!

04-13-2003, 07:32 PM	#2
jmanz69 Careful, they attack... Join Date: Aug 2001 Location: Waterford, MI, USA Posts: 1,107	From what I understand, if you have the time you can put in any GM transmission. 350, 400, 700R4, 4L60E, 4L80E, it's up to you. None of the others besides the 400 will go in without much fighting. Even with a 400 you will have to shorten your driveshaft. Are you looking for overdrive, or is your 350 shot? I had a 350 in my 69 and it ran great, had a 300+ HP 327 in front of it and never had a problem. There should be lots of threads about what transmissions go in these trucks and how to do the swap. I see posts about it all the time. Use the search function and see what comes up. good luck

04-13-2003, 10:03 PM	#3
Rons71 Registered User Join Date: Apr 2003 Location: Saskatchewan Posts: 21	Will a 400 trans fit into the low hump cabs?

04-13-2003, 10:52 PM	#7
Rons71 Registered User Join Date: Apr 2003 Location: Saskatchewan Posts: 21	Do the 400 have a long tailshaft?

04-13-2003, 10:56 PM	#8
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	mine from the 79 c-20 had a short tail shaft and a bolt on yoke they make a aftermarket yoke if you want it to slip on and off..the worst thing is,,,you may have to get a shiney new drive shaft...or front shaftif you have a two piece?

04-13-2003, 11:14 PM	#9
Rons71 Registered User Join Date: Apr 2003 Location: Saskatchewan Posts: 21	I've got the short shaft on my 350 and want to run a 1 piece driveshaft. The driveshaft length is 71" so by going with a long tailshaft and a beefier trans I should be able to run a 68" or so(I think)?

04-13-2003, 11:32 PM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	The TH400 came in 3 lengths, the ones under the caddys are the real long ones, I think the med length 400s came in the 73 and up trucks, but I may be mistaken.

04-14-2003, 06:53 AM	#11
jmanz69 Careful, they attack... Join Date: Aug 2001 Location: Waterford, MI, USA Posts: 1,107	400's are great if you have a ton of HP and torque. If you are running a mild small block, you will be actually losing HP. It takes 15 or so more HP to turn a 400. So you would need a built small block to make it worth it. I mean like 400 HP or more. A 350 can handle 400 HP if built right. Plus they are cheaper and easier to find. As far as other trans options, if you want to go with a stick, almost any GM manual will fit. They of course, take a bit of customization to get them in and you will need a new drive shaft. The Muncoe 4 spds, Borg Warner 4 and 5 spds, Richmond 4, 5, and 6 spds all will go in. I am goin with a saginaw car 4 spd. It's not as strong as a Muncie, but I can buy 3 of them for what I can get a muncie for. It will handle my 327 no problem.

04-14-2003, 09:23 PM	#13
jmanz69 Careful, they attack... Join Date: Aug 2001 Location: Waterford, MI, USA Posts: 1,107	I'm not saying 400's are bad, just not necessary in most cases. The internals of a 400 take more uumf to trun. A 350 is easier for your engine to spin. 400's are the best if you have tons of power, or are towing though. Darn near indestructable. But pricey to buy and rebuild.

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