More engine codes
B Dual standard carbs (only used on non-twin cam engines, obsolete code)
C Californian pollution control (also most of the world)
D Uses leaded fuel (Super) when base engine uses regular
E Electronic Fuel Injection
F Twin Cam (economy)
G Twin Cam (sports) with multiple sidedraft carbs (unless EFI)
H Unknown but never combined with -B or -C
i Single point fuel injection
II Unknown - possibly denotes L.A.S.R.E
J Unknown, possibly autochoke, possibly another anti-pollution control
L Transverse mounted engine (seems to be an obsolete code)
LPG LPG fuel
M Phillipines market (details unknown)
P LPG fuel
R Low compression for regular (not super or premium) fuel.
S Swirl intake ports (only a few made in mid '80s)
S Direct injection & swirl pot pistons (starting from '97/98)
T Turbocharged
U Japanese pollution control (introduction of "U"nleaded?). Engine uses TTC-C, TTC-L or TTC-V.
Z Supercharged
More detail
here