[72projectbird]

Originally Posted by johnta1

Basically, from the factory, if it has AC it had a 3.31 gear.
If no AC it would be 3.31 with TH400 or 3.55 with M20.

These would not show on PHS.

M21 could be ordered and would show on PHS.
If it shows Performance Axle it could have the 3.73 gear without AC.

I think if the 3.73s were selected with the M21 trans, the HD cooling option was mandatory. That's how my 70 is set up.

[Transamric]

Originally Posted by 72projectbird

I think if the 3.73s were selected with the M21 trans, the HD cooling option was mandatory.

Yes, exactly. A mandatory extra cost "option".