i got ynx onthe sticker under my hood of my 1986 trans am 305 tpi it tells me that i have a 5.0 and then says 5.7 v8

 

All I know is that according to the shop service manual, those first 3 letters stand for a "label code", underneath that should be the "engine size", underneath that "exhaust emission family" and finally underneath that "evaporative emission family"
example:
CCF
4.4 liter
C1G4.4Z2HA09
0B3-1