I'm not sure that GM offered an OD in 72. Not to say that it doesn't have one installed. I beleive the last year was 69 which was a full syncro Saganaw 3 speed trans with a BW OD. The OD ratio for that trans is about .70
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine