[guruerror]

I think your reasoning is solid...it must have had bigger tires at some point and had the computer adjusted to compensate for the size difference.

Get yourself a Superchips Cortex programmer...you can adjust your computer settings for the tire size, gears, and other fun stuff.

I'd think you'd have to crack the diff open to determine what gears are in it...unless you know the previous owner. When I went to 37 with the stock gears the truck seemed to take a noticeable performance hit...I had to move to 4.56s to get everything back to normal.