How to tell what yr of engine

[ftwflh]

I am not sure what yr my engine is.the Jeep is a 76 but the engine has points not electronic ignition

 

[BrockGrimes]

The AMC 258 i6 / 4.2l (AMC 258 i6 / 4.2l ) can be identified by the 4th character of the engine build date code ("A", "B", "C" or "M"), stamped into the engine block below and between the number 2 and 3 spark plugs. An engine stamped with "B" is an early AMC 258 i6 / 4.2l with a 7.6:1 compression ratio. "A" and "B" are engines with 1-barrel carburetors, while "C" and "M" are 2-barrel. "M" originated in Mexico.

Check here for more specific info:
http://www.scribd.com/doc/7131539/AMC-Engine-Codes