Suffix Code

Have a question about a suffix code.

[ ATTACH=full]6388094[/ATTACH]

I know what the code means. Flint, March, 22nd, 283CI 195 HP 2BBL Carb.
What does the ER mean? Can't find anything on this. Even in the Green Book.
Cast # on the block is 3849852, 1955-1967, dated C216, March 21st 1966.
Cast # on heads is, 3884520 dated C216 & C46



Anybody know

 

looks like the engine number was stamped twice, in two different places. The faint G then F and R mimic the clear GF suffix, with the added R to indicate it came with a Rochester carb. This was a mid 60s only thing, C, H, or R depending if it got a Carter, Holley, or Rochester carb.

 

Thks Jim