Firstgens.com

I shoulda stayed in bed! I went to work and nothing went right. I didn't make much progress in the AM brcause of a trip to Home Dpo and then I went out again to get a sandwich for lunch and almost didn't make it back to the job. I heard a noise like something shfted postion under the truck and I suspected the gas tank was loose. I stopped and checked and could find nothing loose. Drove farther and heard more noise, checked again and still nothing found. Went in to get my lunch, come back out won't back up, still goes foward so I push it out and off I go. The rpm's are higer before each shift and the shifts don't feel right. Towed it home and dropped the pan, nothing obvious in there. Its a 98 chev C1500 that I drive everyday. Any thoughts?

OK the expert at that "other" place tells me it a 4L60E not the 80 and the sun gear shell broke. I just came back from the auto wreckers with a different trans and leaving soon to buy a trans jack.

I'm no expert on the subject.
I was wondering why your 1/2 ton would have a 1 ton trans in it. Apparently it doesn't.
I'd guess the 4L60E were used in alot of trucks. I once sourced a 4L60E for a Jeep I built for wheelin'. Out of a 95 S10 blazer.
I'd guess you just have to watch the output shaft length depending on if you get one exact from a truck like yours and I'd also assume the tcases are different throughout the years. Not sure if yours was 4x4 or not.

I wish you luck getting it back on the road.