update time
The other day I got my "Rostra" gov sensor and my "HD Borg warner" solenoid in the mail, and my new ATSG book. Today I put it up on my lift, (yes I have my own) dropped the pan, and changed the filter (again) and those gov sensor and solenoid.
The "desired" pressure does just like it did. Jumps straight to 126.8 soon as I pass 34 mph.
The "actual" though does like the original, failed trans did before I swapped them. The "actual" gets to ~75-80 then levels off and falls back a few PSI. It doesn't try to "catch up with" the "desired" PSI like the replacement trans did with the original solenoids that were in it when I got it//. and even the wife noticed, it shifts just like it used to before the original one went bad.

so, I can confirm my beliefs that the trans failure was pure coincidence// and had nothing to do with having the dash out of it just a few days before. I had been pulling my hair out, rechecking grounds and every wiring plug to be sure they were snapped in as designed.

It's just weird the shudder in the original trans started 15 miles, after I had the dash out and back in. the fact that I have 312k miles on this rig, probably has nothing to do with it, huh?
well, the redundant grounds I ran, in trying to troubleshoot this, sure won't hurt anything. I had had much of the dash (back) apart more than once checking things. along with the wiring diagrams on Mitchell On'Demand that we have at work.

I have a few-years-old ATSG book on the 42/44re, and I didn't see much of anything in there about the governor, other than pix of the different sensors and solenoids used thru the years of the "RE series. I just got the "latest" 46-47-48RE book from them, and there it was in black n white. there is a section on governor operation that wasn't in the other book I have....

It never did start out in 2nd or 3rd and "stay there" though, as it said was the usual symptom of gov sensor/solenoid issues. but the new book did describe how the governor is supposed to work in a way that I "got" (understood). and it appears that part of what I was seeing was right, the only part of what I was seeing that wasn't, was the "actual" side of governor pressure. Now it shows on there (the scanner), as should be expected/ at least according to that book. I did head to town and threw a new output speed sensor on there "for good measure". the only thing that didn't get done, was that I bought a new spring for the 3-4 shift in the VB, when I bought the solenoid and sensor, and being we had "somewhere to be" I put it back together and forgot to swap that out. No, I never pulled the cover off, so nothing open, nothing loose in there. But I have found several of those particular springs busted in 1/2, over the years so I was "wanting to" replace it while I was in there,
though it was very obvious that this was a VERY recent overhaul, because I got it from a U pull, I have no idea who rebuilt it, or how extensively. but it works fine. the trans temp reading with the new solenoid and sensor is making more sense now than with the old set in there, as well.

I am gonna have to stock up on trans filters via Ebay, rock auto, etc, This was the 2nd time since I swapped that trans, that I had to pay an outrageous $28 at my local O'Wrongleys for a Wix trans filter.... and then $34 for that output sensor. of course I have 6 of the older, non plastic cased, 904/727/500/518 trans filters here already....
For a trans that I "just had to have" on a sale day at the U pull for $60 with converter (I think core was something like $28 then, besides) like 4 years ago, I spent $157 on the first case of ATF+4 and filter that went in the day i swapped it in, then $120 for the HD solenoids, then another $60 in fluid today and that 2nd filter (the one I bought today) and the output speed sensor, but I think I finally got it solved.