I was able to document many unique things that helps verify the car such as:
Frame Stamped Twice with Vin Seq
Rear End Date Code, and Stamping from May of 66
Harrison Radiator with Date code on the upper tank of D(sorry no picture) and code UN and Lower Tank BP. Side Straps are Dated C(March)
Seems little has been known why GM had a separate tag for the M20 with L78. I think I found why. 2 things that made the L78 muncie M20 different than the regular M20
Stiffer side cover dentent spring, muck like you would see in an M21 or M22
In the following 2 pictures notice the gears are painted differently from the factory(when I cracked the side cover I was like why!?)
I got the slider out and found out why. GM put an M21 slider with the locking groves for 4th gear in the M20 with High performance engine
Trans vin Stamp. Appears to be stamped off line after the car was assembled
Well I hope everyone can enjoy my story and learn as I have. Full Restoration to start later this year! Already have another NOM and plan to have this car back to better than new with a High End restoration