318-3 is cast into the block, I'm not 100% sure which size truck it came from. Being still has the cable attached, throttle brackets, etc, I'm assuming a 1/2 or 3/4 ton. I know that the 318 forged crank 318 time span is sketchy. Some say 71-back. Others, it ended in 68.

Transmission has the cast in bracket holes. It appears to be the same as a 70-340 transmission I have on hand. Truck tranny pan rail numbers: PK28293140 2234 build date (1967 and matches block cast date)

Something else I noticed, is the crossover pipe in front of the pan.