I would say so, yes.
The fact that you have the VIN match on your trans, and the date code falls in line with the car build date gives you extreme confidence that you have the original trans to your car, which would be the Muncie M-13.
Saginaws from that era had the single bolt on the top of the side cover, and they were weaker transmissions, all things being equal.
I don't know what happened to the designs as the later 70's rolled in.
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Eric Mitten
'74 Bonneville 4dr Sedan (455/TH400/2.93 open)
'72 LeMans GT (455/M-13/3.23 [8.5"] posi)
'71 GTO Hardtop (400/TH400/3.07 12 bolt posi)
‘71 GTO Convertible (455HO/TH400/3.23 posi)
'67 GTO Coupe (455/ST-10/2.93 posi)
Deuteronomy 8:3
