4.33 gearing was not avail as an option in the HD 8.2 STT rear in '71 model A-body's. Factory installed,
3.90 was as low as it got for '71 models. That was special order behind non AC 400 4bbl A-bodys. It's also an extremely rare chosen option for '71. I have one copy of a factory invoice of a 400 M22 3.90 special order early 71 GT-37. GTO wise, less than a handful of '71 400 GTO's have surfaced w factory 3.90 gearing.
'71 model T-37's & GT-37 factory equipped with the 455 HO engine received 12 bolt rears built out of the McKinnon plant. Ordered with the 455HO engine, & without factory AC, the gear ratio was 3.55. With the M22 or M13 HD 3spd and factory AC, 3.31 gear was required. No 3.73's, 3.90's or 4.33's from the factory.
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Buzzards gotta eat... same as worms.
Last edited by 'ol Pinion head; 01-31-2021 at 10:22 PM.
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