1990 k3500 Opinions and Transmissions?

Joeleodee · August 29, 2017

Hello all.

I'm in the market for a 1 ton truck from this generation of Chevys.

There's one in particular I found somewhat locally, but I'm a bit confused. It's a 4x4 dually, 7.4ltr engine, auto tranny with under 75k miles on the dash. Upon inquiry, the seller sent me additional photos. One of the photos was a close up of the dash. Now, in my findings, the only transmissions available for the 3500 were the standard 4 speed, and the TH400 automatic. However, on the dash, the gear indicator had the 1, 2 , D, and OD (D with the circle around it). Was there another overdrive transmission offered in the 3500 series that I'm mistaken on? The other OD transmissions of the era were the 700r4 and the 2004r, but I wouldn't think they would put either of those into a heavy hauler dually pickup because those were not rated for that kind of duty. It's also my understanding that the 4l80e was not offered until some year after the 1990 model year. I haven't been able to inspect the truck in person yet so I can't check the pan to tell me for sure what's in there. If it's one of the weaker transmissions, I don't know that I want to waste time driving more than an hour away to look at it, unless my perception of those transmissions is incorrect.

Anybody have any idea what I'm missing?

Otherwise, I'm in this market because I'm looking for a reliable hauler for occasional work purposes, to trailer my project vehicles, and other general utility purposes. Am I on the right track with pursuing something from this lineup?

Motor City Rick · August 29, 2017

99% chance it's a 700R4 "truck trans" being a dually / 7.4L / 4x4. Have the seller take a picture of the trans pan to see if it's a 400 or a 700R4. Then compare the pan picture to pan shapes on the internet. If the trans / motor is leaking like a sieve, walk away. It tells me the truck was put away wet.

According to GM, the 700R4 transmission was first introduced by General Motors in 1982 and used up through 1992. It is sometimes also referred to as the 4L60. The 700R4 was one of General Motors first over drive automatic transmission and was used in everything from Corvettes to pickup trucks.

In my personal opinion, the 700R4 trans is one massive piece of sh*t. They have a lot of problems, Expensive to fix. Poor reliability, etc. Here is a link for a summation.

http://etereman.com/blog/general-motors-transmission/what-you-need-to-know-before-you-buy-a-gm-with-a-700r4-transmission

https://itstillruns.com/problems-700r4-transmissions-7304243.html

If you every go the 400 trans route, look for a 400 "truck trans" out of anything bigger than a 1 ton heavy duty truck, ...not a car trans. Then install a 6 pass (or more) trans cooler for the work you want to do.

The numbers in front of the trans designation were the foot pounds of torque rating. 700 equals up to 700 foot pounds of torque, 200 is up to 200 foot pounds of torque which was a bubble gum trans for light duty cars. The "e" suffix on a trans designation means it's electronic and controlled by an ECM.