Best magnum MPG?

CC is club or extended cab.

IIRC 3.92 was the standard gear for the R/T.

The guy I'm talking about bought the truck new, and is good friends with a local Mopar head mechanic that I've known for 20+ years and trust implicitly.

Why would he need to special order the stock 3.92 ratio?

My truck will get 23 MPG at 50 MPH, any slower is worse, any faster gets progressively worse.

This is all via the EVIC, which I verified three times. It is actually off by .5 MPG over three entire tanks, but in my favor, IE- EVIC says 13.4, but the math says 13.9, again over three tanks, so IMO it's pretty well "on". I also verified with a "scanguage II" which confirmed my findings.