ST72 - 1972 Model year (STyle 72) 4 = Buick Motor division 34 - GS 350 37 - 2dr hardtop FL1 - Fisher Body Flint 1 173561 - Fisher Body body number T2 (probably really TR) - Trim 138 (black buckets) 48B - Hunter Green with black vinyl top 02 (February) 2 (2nd week) A51 - I always forget....buckets?
Unkike in '68-70 (maybe only '69-70?) when GS 350 ("34") & GS 455 ("46") were different series, "34" in '71-2 is technically a GS, not a GS 350. The 350 was the standard engine in a GS and the 455 & Stage 1 engines were optional. Hence the difference in the air cleaner decals in '70 vs. '71-2 as well.
(*there was no 455 for 1968 and 1969) Yep, it also says only GS in the 1972 (Canadian) brochure, with 350 or 455 engine options: