My TH350 is shot, right?

[JMD]

Hi all,

I put a TH350 in my '68 K10 that was in unknown condition. Bone stock 454 in front of it, and an NP205 behind. I changed the filter, and put a B&M shift kit in it, but other than that I didn't touch it before I stuck it back in the truck. For all I know it could be the original trans. I put about 1200 trouble free miles on it and it worked flawlessly. It would chirp the tires going into 2nd, and the 2-3 shift was pretty crisp as well.

Recently the 2-3 shift became pretty soft, even under light throttle. It got to the point where it would spend over 2 seconds between gears, so I knew something was up. I checked the fluid, it was full and didn't look or smell burnt. The kickdown cable was also adjusted properly, so I just kept driving it hoping it was all in my head.

Fast forward to earlier this week and the truck wanted to hold onto 2nd gear way too long, and I had to let off the throttle completely to get it to shift. Once in 3rd it would hold it no problem. Once in awhile it would shift fine though, and it seemed to shift better under hard acceleration (firm, quick shift)

Today it refused to go into 3rd unless I really played with the throttle and revved the engine quite a bit. If it did shift, any throttle at all would cause it to slip out of third. I also noticed that reverse is slipping quite a bit. From what I've read online, these symptoms together indicate that one of the clutch packs is shot.

Is it time for a rebuild? I was planning on rebuilding the whole thing eventually, but I wanted to make it through fall and work on it over the winter when I can't be driving it anyway. Anyone have some an idea of what else it could be?