Stalls when put into gear

Merlin 2021, Thanks for the help, now a couple of more questions. Where is the TCC solenoid located, and why are you questioning brake lights? Thanks for the help, you guys are fabulous.

Brake lights work. First tech want to r&r transmission.
After road test, transmission shop owner says he is 85% sure problem in electrical. I did not care for first fellow, he seemed intent on transmission overhaul. He said that the transmission coded there was no electrical failures within transmission. He also said he unhooked the electrical to transmission and it was the same thing. That made no sense. We are new to this area, and do not know any technicians, that always makes it tough. Any suggestions as to what you would guess? Thanks, you have been great.

Mike the first fellow, said he ran the transmission on a "transmission computer". I had never heard of anything like that. He was not answering my questions directly and I felt he was trying to sell me a transmission. He did say that he "unhooked the transmission electrical, and the converter did not unlock. He did not pull the left front wheel off, and did not pull the inspection cover off of the transmission. He did not offer codes, and I didn't ask, he charged my son $85.00. We left.
The tranmission shop owner said he was "85% sure the problem was electrical, and looked at our bill to see if there were any codes. There were no codes. I would have thought we would get a code or something. Our transmission shop charges $25 for the diagnotic test. He says if it is electrical, it should cost about $300 to repair. Your thoughts?

Odd that you ask about the code readers. Mike, I asked about the pruchase of one, and was told it was not a good idea. It had caused people to install parts that were not needed because they read codes that were not it the proper sequences.
I don't do a lot of work, anymore, mainly because I don't have time or understand it as well in today's world. I also own a 2008 Lacrosse Special (love those V8 engines) a 2000 F-150 4X4, and a 1966 Volkswagen Beetle. Is there a particular brand or type of scanner that you would recommend? I just checked on this a few days ago, because of the Lincoln problem, and was talked out of it. Any help you could lend would help immensely. Do all of the reader plug in under the dash, or is there a computer just for the transmission? Thanks merlin, you have been a lot of help.

Thank, Mike. I let you know how this comes out.
I just wanted to say that I went to my first mechanic, I found him online, and he had the highest rating and the most responses. I think he might have posted them himself. Lol. I found the transmission shop, by accident, asking a professional parts man for a referral, because I was so new to the area. This has been a very good experience, I've learned a ton, in the last couple of days. Mostly, from you.

Merlin2021, my 94 shuts off when I put it in drive. Reverse works as it should but drive just stalls out. And brake lights do not work.