When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I actually just had it done at my local dealer. They gave me a good price on the T-lok and 3.73s (ford racing), about the same as online sites. And they charged me 4 hours labor max. (It should be about the same if you are doing just the T-lok or the gears as well and it is generally recomended that if you are having work done on the rear end to do both at once). Oh, they were charging about $90/hour.
You're actually not swapping out your 7.5" rear end... you're swapping out your open differential (stock) for a limited slip differential (t-lok)... this is all in the 7.5" rear end. It's a great mod!