[north]

[QUOTE='ol Pinion head;6264941]To answer your first question, all '70 model PONTIAC 8.2 SAFE-T-TRACK-HD rears were 3.90's & 4.33's. Look at a few original invoice copies, all '70 model HD STT rears will have a retail billing of $63.19 & were either in RA4 cars or were special ordered (often behind an M21) in a base horse or RA3 GTO. A factory installed 4 pinion STT carrier, alone, does not make a HD STT rear. In the '69 & '70 GP Pontiac 8.2's, the mid ratio (typically 3.23) 8.2 STT rears all were of a 4 pinion carrier design, but center hsgs were gray iron & axles were std duty verions. Disassemble & reassemble a bunch of these later Pontiac 8.2 rears & it becomes clear, the PONTIAC 8.2 10-bolt 3.55 SAFE-T-TRACK rears while sharing the N housing & 4 pinion low ratio carrier, do not originally have the HD forged axles used in the HD STT 8.2 rears.

My experience is in 69's, are you saying that in 70 only the 3.90 and the 4.33 were billed as HD STT? For sure in 69 all STT's with 3.36 or numerically higher were 4 pinion and billed out as HD at $63.19.