I know I want to change out the 3.08s in my '13, 5.3, 4wd Tahoe, just not sure if I want 3.42 or 3.73.
Hey Dave, I think we've chatted about this before, I'm in the midst of doing the same thing. I picked up a used front axle with 3.73 gears and have put 3.73s in a 14-bolt 9.5" axle. My weak constitution causes this project to be dragged out. Too hot outside now, so I'll probably have to wait until September at the earliest to complete it.
3.73s will give you that extra capability on the steep grades and less downshifting on overpasses and small hills. Someday I'll either supercharge the 5.3 or put a 6.2 in it so it will be identical drivetrain wise to my pickups and be even more capable and fun!
I'm curious to see what the 3.73s will do for my 60-foot times at the drag strip too.
Don't "think" the steeper gears will affect mpgs if at all. As it stands now, my truck gets better gas mileage going 77-78 mph than 70-73 mph, it likes the additional load on the engine. I had a Pontiac that was the same way. Of course, once the 14-bolt is under my truck and broken in, I'll start all manner of testing and share it with y'all here.