Same with this 68 Camaro. 2 sizes of stamps. So there are 2 stamping dies that are used.
Partial VIN is "18U199887"
The partial VIN can also be on the oil filter flange instead of on the pad with the engine code.
The 70 should be stamped on the pad and by the oil filter flange. Where the 68 may only be in one of the 2.