There is a pretty simple way to pull 40's w/ 4.10:1's...

This guy named Marlin's got a web site. <img src="/forums/images/graemlins/notooth.gif" alt="" /> A 4.7:1 x 2.28:1 dual case set with a final ratio of 170:1 or so will pull 40's just fine off road.

If you get it, seriously get it w/ 5.29's or 5.71's they will break. There is no doubt about it.

AZ Rockcrawler site - home of the BTG crew

Granted, these guys are NOT ordinary wheelers, and while I don't wheel as hard as they do, my rig been treated gently.