Slant 6 engine boss decoding

When You get that late in eng. ID stampings, they started including single character codes for base/mid/high line optioned cars. I'm fairly certain all cast crank units have the
"E" stamped directly after"225", .....what kind of vehicle are we working on here? Due to popularity, the A-bodies overlapped the F-bodies a bit,...so a late '76 build date
wouldn't be a shocker, as that was the final model year for them.