Cast number ID

That is the engine serial number on the front of the block. (Not to be confused with the partial VIN)

H - Series (model year) 1972
M - Mound Road assembly plant
340 - 340 CID
R - Regular fuel recommended
3693 - Engine final assembly date - September 7, 1971 (1972 model year)
0152 - 152nd engine assembled at the plant above on the date above.