ugg...having some transmission issues.

v8 4x4. Around 200k miles and for a year or so Ive been having a delayed shift from R and N into D. I replaced the drive shaft and it seemed to help a little, but the delay was still there from time to time. (I also flushed the trans fluid and replaced the filter about a year ago but the delayed shift was still happening before the flush. Fluid level is correct)

A month or so ago it started delaying the shift from 1st to 2nd occasionally, and when it did shift it was a hard shift.

Within the past week or so that delay has increased with higher rpms and seemed to be from 1st to 2nd and maybe 2nd to 3rd. Sometimes it wont shift and I have to bring the rpms down and up until it catches the next gear. Occasionally it throws me into limp mode now too.

Pulled a code P2714 Pressure control solenoid D stuck off. (SLT Solenoid) so I replaced that. Tested the old one and it was fine (5.6 ohms and worked with 12v applied)

No improvement with the shifting. Then threw another code.. P0771 solenoid E stuck off as well as the P2714 again.

I pulled valve body and installed a full transgo rebuild kit as well as an accumulator piston and a pr boost valve. No improvement.

When I had the vb out I looked at the clutches and they seemed to be fine without anything blued or burnt. Also nothing in the pan as far as metal...just a tiny bit of metal dust.

If I did need to swap out the trans, what vehicles can I use as donors? v6 and v8's the same trans?....just as long as its 4x4.

Thanks for any insight!