Trans swap?

5

Asked by Apr 08, 2009 at 09:52 PM about the 1990 GMC Sierra 1500

Question type: Car Customization

My truck has the 700r4 trans and I cant get one but I did find both the 350 and 400 at my local juckyard at a price that I can afford. Now will either of these work in my truck? I know after searching online that with the 400 I would have to get either the 9" tail piece or a longer driveshaft but what about the electrical connections? Will the truck still run right with these other trans in it?

3 Answers

165

The 700r4 is a fully hydraulic transmission, no wires or transmission control modules to worry about. Depending on the engine you have, a turbo 350 should run in your truck no problem. The 400 isn't as much of a bolt in as the 350 though. Also, keep in mind the 700r4 is a 4 speed transmission, and the 350 is a 3 speed, so your fuel mileage will suffer. But, the 350 is a lot more bulletproof than the 700r4. It all depends on what your willing to sacrifice.

45

i would try my best to get a 700r4 because you will of course get better mpg but you top end will be great now if your pulling something the 700r4 is still good but the th400 if u get an older one will near about be indestructable its greatest power is in the low ranges though but i personally like 700r4 i have a shift kit put into mine and it is an automatic and a stall converter it have never given me any problem and i have a greater top speed compared to a th400 or th350

I need a good tranny for a 94 gmc with a 6cyl ....and one for a 88 chevy with a 350

Your Answer

Sierra 1500

Looking for a Used Sierra 1500 in your area?

CarGurus has 65,552 nationwide Sierra 1500 listings starting at $2,495.

ZIP:

GMC Sierra 1500 Experts

  • #1
    dragonflyoffshore
    Reputation
    5,360
  • #2
    John Saffrahn
    Reputation
    3,700
  • #3
    Glenn Clingenpeel
    Reputation
    3,380
View All

Related Models For Sale

Used Ford F-150
2,316 Great Deals out of 184,576 listings starting at $699
Used Chevrolet Camaro
416 Great Deals out of 30,918 listings starting at $3,550

Used Cars For Sale

2017 GMC Sierra 1500 For Sale
76 Great Deals out of 29,751 listings starting at $18,033
2016 GMC Sierra 1500 For Sale
107 Great Deals out of 3,829 listings starting at $15,681
2015 GMC Sierra 1500 For Sale
144 Great Deals out of 4,922 listings starting at $16,900
2014 GMC Sierra 1500 For Sale
136 Great Deals out of 4,948 listings starting at $14,204
2013 GMC Sierra 1500 For Sale
72 Great Deals out of 2,044 listings starting at $8,450

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.