Trans swap?

5

Asked by akaneo 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?

10 Answers

275

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.

6 people found this helpful.
115

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

4 people found this helpful.
30

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

3 people found this helpful.
50

I’m looking to get a th350 HD from 69 camaro shift kit 2200 converter 2wd tranny currently have 2wd 4l60E in a 94 c1500 350TBI wondering if it’s worth the swap as current one needs electrical work and just old Suggestions?

5 people found this helpful.
880

I have a 97 C1500 Suburban 2wd and the 4L60E is so EXPENSIVE that im wondering what i would have to do to get a 700R4 to work in my truck properly? bbenson7146@gmail.com Email me any suggestions or if you have done this swap..........

8 people found this helpful.
880

If i use a 4L60E from a 99 suburban in my 97 suburban will swapping the computer allow it to work properly since they're primarily the same vehicles other than trannies?

11 people found this helpful.
90

I have a gmc 1500 2wd with a 4.3 v6. What size transmissions can i put in it?? Im have a issue finding the 4l60e

9 people found this helpful.
80

Have a 1986 k1500 got a 1990 700r4. What is the 4 pln connector on drivers side of trans can't find a wiring solution

8 people found this helpful.
10

Let me tell thes fools a few things about a 4l60e trans swap with a 4l80 gmc the are numbscal first of lets take the gmc sierra 2002 4.8 liter 4x4 a few things about it # 4x4 transfer case is ventilated chevey 4l60e transferr is not 4l80 belousing fits on a 4l60e transmission please do not use ether torq converter unless your a machinest 4l60e bellhousine is approximately 1 inch sorter so ether you look to your hart content and have the money to pay for the adaptor plale go for it it will fail wana know more emal me zztop321@yahoo.com Ok

1 people found this helpful.
10

Before installing Or buying , a transmission , that isn't the exact one that you are removing , check the spline on the input shaft , it's what goes into the torque converter , then check the out put ( tail shaft) shaft, they could be 30 spline or 28, next check the overall length from tip of input shaft ,to tip of out put shaft. , your transmission has to fit between the engine ,and drive shaft, if it does'nt , you may need to shorten the drive shaft or lengthen it ( not worth the cost) .

1 people found this helpful.

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