hello, i have the above listed, it's a work truck, runs great. The guy i got it from said the computer won't let it shift....it goes 1,2 and.......
2,....i really would like some input on this because i got plans for it...
i think it would make a neat project....Thanks Jon :cool:

Pretty sure a 91 would have a 700R4 which is not computer controlled. Of course, it could have a newer 4L60E which is computer controlled.

Usually, when there is no shift into 3rd (especially on a work truck), it means the 3-4 clutches are gone. If that is the case, it needs to be rebuilt.

//2000CAYukon

he's right, it's a 700r4, 4l60e was introduced in late 92, your 3-4 clutches are out, look into a rebuild or replacement.

91 3+3 is a one ton and should have a 4L80 not the 700r-4.

Rene

Ya, the 700R4 is a VERY light duty tranny and not usually found in 1 tons.

Ya, the 700R4 is a VERY light duty tranny and not ever found in 1 tons.

fixed it for you.

Rene

Without crawling under the truck you can tell if it has a 4l80E or turbo 400--If there is a second relay on the firewall by the fuel pump relay identical to the F.P.Relay then it has a T-400--If not it has a 4L80E