Help with 90 Sierra Tranny
 

Hey everyone!

Well, my pride and joy, my 1990 GMC Sierra 1500, needs some help. I was driving the other day, and I have a problem with third gear. It's and auto, and you can hear it shift fine from first to second, but it gets really high RPMS in third, and when it shifts to third it sounds horrible. If I get it up to 40 mph and left off the gas, it shifts into forth and its good to go.

So, I figure I need a new tranny, right? Well I called a junkyard, and they said i have one of two types of trannys, but I don't know witch is witch. Can you tell me what I have, or how I can find out?

1990 GMC Sierra 1500, 350, 2 wheel drive. Any ideas?

4l60, not the 4l60e. Also known as the 700R4. They made the same tranny until 94 I believe when they added all kinds of electrical garb, hence the e.

Good luck