I'm not trying to hijack this thread, but I've got a factory 4.09 ratio front diff to swap with my 3.55 diff. But I was just going to have the gears swapped in the rear. On Randy's site, the Yukon gear only comes in 4.11, why not 4.10?

 

I would pull the cover on that 4.09, and count the teeth, and do the math...... probably gear ratio is also etched into the ring gear somewhere. Clean it off and have a look. Rather an odd ratio for a dodge, wasn't available from the factory that way, and all I have seen for 'em is 4.10's. (maybe someone is doing some different rounding?)

 

4.88s, my dodge runs like a champ.

 

RING GEAR: 45 PINION: 11 (45/11=4.0909090909 and so on)

 

now with 35's changing my gears to 4.1 or 4.56 wont change the mpg will it?

 

With 35's, going from 4.10s, to 4.56 will probably get you BETTER mileage.