Chevy 4x4 Transmission question

[lonnie]

Hello,
I recently purchased a 1994 Chevy 2500 4x4 light duty truck. (it has only 6 lugs). I am pretty sure it is in need of a transmission. It was slow shifting in to overdrive, I changed the fluid and filter, I put in B&M trick shift fluid. It started to shift fine for a short while, then it was shifting hard between gears, now it does not want to shift from first to second without letting off the gas, some times it slips while going straight down the road. The pan has 16 bolts. I am told the truck has a 4L60 or a 4L80 trans. I do not know which one it is, can I tell with out pulling the trans. Also I found a rebuilt one from a 1995 4X4 Truck on e-bay and the guy tells me that the pump was changed from 94 to 95 and this will not work. Does any one know if this is true? Any help will be greatly appreciated.

[mrjohnwayne]

If the tranny pan is square than it is the 4L60E (700-r4). I can't remember what the 4L80's looked like but it is a very noticable difference btween the two. It should also have a big gray plug with alot of wires(at least 20) on the passenger side just behind the coolant lines. If i'm not mistaking the 4L80's plugged in on the driver side. As for the pump's being changed from a 94 to 95 I don't know about that. I would suggest having it rebuilt locally before purchasing one from ebay. Just my .02 Hope this helps