1911
chupacabra
So ended up just pulling the diff and counting teeth. its not 4.11 so now im really pissed at the PO as nothing about what he claimed it to be is correct. its a pre 79 not an 85, and its 3.7 not 4.11. which is strange no? shouldn't the pre 79 have 4.11 in it? to confirm, 4.11 would have 10 teeth on the pinion yeah? this one has 9.
To get the 3.70 ratio of the '79 and up FJ40, Toyota used a pinion gear with 10 teeth and a ring gear with 37 teeth, which is why the ratio is exactly 3.70, not the 3.73 that lots of guys are used to with detroit-made diffs. So if your pinion has 9 teeth, it is not 3.70, but most likely a 4.11.
It could be argued that the 10-tooth pinion is stronger than the 9-tooth pinion because the diameter is necessarily larger, but the difference is not much.