Well, on the 97 SR, I will without a doubt do both t case gears and diff gears. My question was mainly for my 97 LS that has the tow bar on it. I was thinking not to use the SR for towing a trailer b/c I wanted to set it up for wheeling only, so I wasn't going to put a receiver on my custom rear bumper design for the SR. My LS already has the tow package put on it (I did it long ago) so if I eventually get a trailer to tow quads and stuff like that, I was planning to use the LS. At most, it would have 32's on it and it has the 4.272 gears in it. I already towed a total of 10,000 lbs (vehicle plus trailer) accross the country with my LS when I moved out here and it had 32's on it. It did ok, but definately needed 3rd gear to go up hills on a highway and couldn't really keep up with traffic. I am starting to think that it might benefit me to put 4.90's in my LS for towing purposes, but was wondering if it would kill my regular driving gas mileage when I didn't have any weight in it. I suppose in time, maybe I will get the 4.90 gears for both my LS and SR. Opinions?