I need some info concerning a OD tranny swap and tranfercases. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BarryB · 01-11-2009, 05:51 PM

I have a 86 Chevrolet 1/2 4wd truck. I believe it had originally an overdrive tranny in it. Reason being it has OD on the column shifter, and the rear driveshaft looks to be 2-2.5 inches to short. It has a T350 in it now, but its bad. So I heard that in order to hook a 700r4 to the transfer case I would need an adapter. See I am not for certain they didn't swap the case when they put the 350 in. are there numbers to look for to see what type and year it is, I am wanting to put back in the OD so I can get a little better MPG on the HWY. But don't want to spent a fortune doing so.
Hope you can make since of what I trying to explain.

skchevota · 01-11-2009, 11:12 PM

700 r 4 will bolt in place of a th350, you can use the same t case. you will need the 700r4 TV cable. If you dont hook it up correctly you WILL burn up your tranny in a matter of a few miles.

BarryB · 01-12-2009, 02:47 AM

So basically there all the same all the years?

*FormerMember* · 01-12-2009, 09:13 AM

Quote:

Originally Posted by BarryB

So basically there all the same all the years?

No, they're not.

Outer dimensions are the same, but the earlier transmissions suffered many internal failures. If hunting for a 700R4 go for a 86 and later transmission. Up to 91, will all work. In 91 Gm changed the name to a 4L60, but it will work for you. Your truck should have had a 700R4. BTW, a 700R4 will NOT bolt into place where a TH350 was from the factory! The 700R4's tailshaft is longer and will bottom out on the t-case before you can bolt it together. The tailshaft housing that bolts to your T-case will fit a Th350 and should physically bolt up. Problem is, you wouldn't have enough spline engagement, as the Th350's tailshaft is shorter than the 700R4's. So in a nutshell, you can put a Th350 where a 700R4 was, but not reverse it without building a spacer, swapping out the tailshaft for a custom one or cutting the factory 700R4 tailshaft.

BarryB · 01-12-2009, 12:26 PM

Thanks grendel, It had to had a 700 in it before because the driveshaft is too short. I can see atleast 3" of drive shaft yoke sticking out of the transfer case. So it makes since that it had originally a 700 in it. I had heard about the newer 700s so I will look for a 86 up. Thanks

01-11-2009, 05:51 PM	#1
BarryB Senior Member Join Date: Jul 2006 Location: Blountville, Tn. Posts: 3,904	I need some info concerning a OD tranny swap and tranfercases. I have a 86 Chevrolet 1/2 4wd truck. I believe it had originally an overdrive tranny in it. Reason being it has OD on the column shifter, and the rear driveshaft looks to be 2-2.5 inches to short. It has a T350 in it now, but its bad. So I heard that in order to hook a 700r4 to the transfer case I would need an adapter. See I am not for certain they didn't swap the case when they put the 350 in. are there numbers to look for to see what type and year it is, I am wanting to put back in the OD so I can get a little better MPG on the HWY. But don't want to spent a fortune doing so. Hope you can make since of what I trying to explain. __________________ We could learn a lot from crayons... Some are sharp; some are pretty;and some are dull. Some have weird names; and all are different colours;but they all have to live in the same box. You may be only one person in the world, But you may also be the world to one person. * Some mistakes are too much fun to only make once. Two rules in life. 1. Never sweat the small stuff! 2. Everything is small stuff!

01-11-2009, 11:12 PM	#2
skchevota Registered User Join Date: Oct 2006 Location: Evans, Colorado Posts: 530	Re: I need some info concerning a OD tranny swap and tranfercases. 700 r 4 will bolt in place of a th350, you can use the same t case. you will need the 700r4 TV cable. If you dont hook it up correctly you WILL burn up your tranny in a matter of a few miles.

01-12-2009, 02:47 AM	#3
BarryB Senior Member Join Date: Jul 2006 Location: Blountville, Tn. Posts: 3,904	Re: I need some info concerning a OD tranny swap and tranfercases. So basically there all the same all the years? __________________ We could learn a lot from crayons... Some are sharp; some are pretty;and some are dull. Some have weird names; and all are different colours;but they all have to live in the same box. You may be only one person in the world, But you may also be the world to one person. * Some mistakes are too much fun to only make once. Two rules in life. 1. Never sweat the small stuff! 2. Everything is small stuff!

01-12-2009, 12:26 PM	#5
BarryB Senior Member Join Date: Jul 2006 Location: Blountville, Tn. Posts: 3,904	Re: I need some info concerning a OD tranny swap and tranfercases. Thanks grendel, It had to had a 700 in it before because the driveshaft is too short. I can see atleast 3" of drive shaft yoke sticking out of the transfer case. So it makes since that it had originally a 700 in it. I had heard about the newer 700s so I will look for a 86 up. Thanks __________________ We could learn a lot from crayons... Some are sharp; some are pretty;and some are dull. Some have weird names; and all are different colours;but they all have to live in the same box. You may be only one person in the world, But you may also be the world to one person. * Some mistakes are too much fun to only make once. Two rules in life. 1. Never sweat the small stuff! 2. Everything is small stuff! Last edited by BarryB; 01-12-2009 at 12:27 PM.



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