Thanks I was pretty sure it wasn't The original motor. By partial vin are you referring to the numbers casted on the other side of the block? Also since it is a post 65' block any transmission after 65' should bolt right up then correct?
The combustion chamber shape was slightly modified for 1967 to promote more complete combustion and reduce exhaust emission toxicity.
All G engines used forgedsteel crankshafts until the middle of model year 1976, when a less costly cast-iron crankshaft was introduced. The cast crankshaft uses a different block, different main and connecting rod bearings and different connecting rods.
The counterbore in the rear flange of the crankshaft was a 11⁄4-inch diameter until 1967. For 1968, it was enlarged to 11⁄2 inches. This difference has implications when swapping engines and automatic transmissions across this date line.
All G-engines used solid valve lifters through the 1980 model year, with the exception of a small production test of hydraulic lifters in the 1978 model year. For model year 1981, all North American G-engines received top-fed hydraulic lifters. Retrofitment in both directions is possible.
Emission control devices and systems, carburetor make and specification, and engine assembly details changed over the years to comply with market requirements and preferences.
Electronic ignition, which had been made available on V8 engines late in 1971, was made standard equipment on all engines including the RG in 1973.
Induction-hardened exhaust valve seats and upgraded exhaust valves were made standard in 1973 to withstand prolonged operation on no-lead fuel.