I have a 2001 4T65E, 200k + miles. Delayed 1-2 shift and decent 3-4 shift. No 4th due to stripped 4th splines (I'm quite sure-rpm's drop to idle when letting off gas). After awhile it goes to hard shifts but can remain in normal pressure mode with soft shifts for a long time. No noticeable slipping. To give the trans a couple more years of use, I would like to replace the 4th hub myself, and while it's open I'm considering replacing all the solenoids, definitely the PCS. If I do this, would a shift kit on top of new solenoids be beneficial? Help in any way or hurt?

Thanks!!!