My M-code notchback is coded T75, CO1 SPD (12/1/68)

So GG book states:
all these are E70x14
T72 WSW 2P/4P
T73 RSW 2P/4P
T74 WSW fiberglas
T75 RSW fibreglas

So T72, T73 are likely Firestone wide oval white and red streaks.
T74, T75 Goodyear fiberglas/polyglas.

I have a '69 340,4spd Swinger BS coded T62 which is D70x14 WSW 2P/4P
I know for a fact that GG books are not 100% correct.

I'm the CARETAKER of Weinstats '69 440 'cuda registry and have 104 of the 360 cars to date. 84 fastbacks/20 coupes. Always looking for new(REAL M-code) '69 440 'cudas to add to the registry so drop me a note if any are found or known. This isn't a publicly released registry. Thanks, Dave