Factory ratio is 4.10, tire size is subjective. I ran with 35" tires for a while and that included towing a 3500 lb trailer through the white mountains with factory gears. It was what I expected and I dealt with it. I now run 4.88s and am much happier.
Not worth the effort and expense unless you are 100% sure you will never go back to stock tires and never get larger tires. Just go 4.56 or lower or don't bother. Setting up a diff typically costs around $250 plus bearing kit. You will save some dough if you bring the 3rd member to the shop.
As I stated I now have 35" tires with 4.88 gearing. This gives me a slightly lower than stock total ratio for the truck. The driveablity of the truck this way is far better than the stock ratio. If you are going to go with 33" tires and regearing also I'd go with 4.56 gears. This will put you about where I am now at a slightly lower total ratio and give you some room if you want to go with 35" tires later which would return you back to stock.
I got my gears from Randy's R&P. Both sets with bearing sets where about $800.00, about the price of a single set of factory gears w/no bearings. Install would be about $1000.00, I chose to have my front axle overhauled at the same time and the labor was $1400.00.
A lot of us are running 35" tires and 4.88s. I personally think this is the ideal setup. The rub issues aren't that prevelant and the driveability is fantastic.
I'm curious how your Truspeed™ recallibrator manifests itself within your setup . Might be a good tidbit to differentiate for us how the T.R. changes things ; if you even have it setup still . I know you can set it up for gear size and tire size (both) . And if you have kept it online , wouldn't the driveability seem enhanced (over stock) from 2 gear up only ? IOW's won't your 80 fly off the line , but then settle back into thinking it's running stock gearing ??
Tyler -- still trying to twist my head around gears and computers *L*
I still have the truespeed installed but now setup for the 8% total change of both the tires and the gears. As the truck's computer reads rpm and speed to chose an ideal shift point, unlike the favorable response of holding shifts longer when you don't regear there is no adverse effect when you do because the regear shifts the torque band down in the rpm range so when the truck shifts sooner the torque is available there mechanically.
Hope this helps. You've got the 35s and the truespeed already, treat yourself to a set of 4.88s, YOU WILL NOT BE DISAPOINTED!!!!
You know ... I think I almost understand that *L* . Seriously , if I ever crawl from under this debt load long enough ( and I don't blow a wad on a chopper ) I will treat myself to some gears ... and a set of Slee bumpers . Oh and a snorkle and umm .. : :-X :-\ :'(