Transmission Rebuild Decode

A buddy of mine gave me what he says is a GM 400 Turbo.

I'm going to hook it up to a 350 http://www.yearone.com/serverfiles/fbshopmain2.asp?input=8512N&SM=1&SC=&goBtn.x=0&goBtn.y=0 (8512N) and have a 3.83 posi in the rear.

The drive line I have needs a yoke adapter, but I'm trying to verify the transmission type first.

I've seen the General Motors Corp stamp along with the number 8623462, I think this is the case number.

Also, there a small plate on the passenger side that reads

502
71-CJ-17861

According to http://www.nastyz28.com/chevy-transmission-identification.php it looks like a THM400

Any help on identifying would be appreciated.