Help on this set of numbers

[Flowjoe]

CAst number = 3849852 = 283CID
CAST DAte = D 9 4 = April 9th, 1964
Pad stamp = F06I2M = Flint, June 12th ?

What does the M stand for?  Have only found one reference to M as a suffix - 1958 Truck 283, which this can't be

thanks

[bertfam]

"M" = 1964 283/175 2BBL with a Manual Transmission from a C10, C20, C30, K10 or K20 Truck.

Ed

[Flowjoe]

Thanks Ed!