Well, my shift kit is on the way, along with replacement pistons if needed. I spoke with a local certified tranny rebuilder (20+) years experience and explained my issues, to which he was obviously familiar.
I am volleying the tranny service, and install of shift kit parts to him, as he is only going to charge $60 for fluid / filter change, and install of accumulator shift kit parts, so long as I provide him with kit, fluid, filter, etc. He's got the shop, all proper tools, lift, etc., and says he can have it done in about an hour's time.
I did the initial fluid / filter change at around 100K, and had it done again at 174K; so it hasn't really been neglected.
I don't have a garage, and would be doing it in the driveway (still a bit chilly here in MI), and it would probably take me 2-3x as long as him to get the job done. I figure it is worth the $60 labor to have it done right by a certified rebuilder.
I have put just shy of 200K (just turned over 245k yesterday; bought the car with 47K on it) on the tranny, and have been having the hard shift issues for a while now. The tranny has not been abused, raced, etc. I drive very conservatively, as this vehicle is my DD, and work vehicle, so I depend on it and treat it accordingly.
I don't get the hard shift issues all day / every day. Some days it will shift fine all day, some days only part of the day it will shift hard. So it is a random issue.
Anyway, thank you for your .02.
Correction its upgraded springs (more of them) and some "spacers" not shims.
The shift kit does indeed fix the "harsh/max adapt code". Haven't experienced either since I did my trans go kit. I do still have some major slipping during initial startup on cold days. I believe I didn't scuff the accumulators enough and it needs another fluid change.
However yes indeed these transmissions have PCS and shift solenoid problems but, only because people don't maintain (fluid changes) often enough. These tranny's should have fluid/filter changes NOT flushes every 40-50k miles to be safe. GM says 100k miles but that's bull crap.
My transmission had never been serviced and I made the mistake of having it flushed at 130k miles. Very next day and on I had max adapt/harsh shift issues.