Engine ID needed and GMC model

[51GMC]

Hello. New to mortec. I just bought a 51 gmc with a engine with casting number of 3970014 and on the front of the block is engraved T0401CHY
Also if anyone can help determine the difference between 100 model and 100-22
Thank you

 

[Philip]

CHY decodes as a 1977, 350, 170 hp, auto trans from a police car