I have an 04 SCrew with the 5.4 and 3.55 NLS gears. Couple of questions (please). Would it be worth time and money to switch to 3.73s or should I just go ahead and go with 4.10s. I use this truck for normal driving and boat towing. Is something me and a mechanically inclined friend could do or is this a pro shop kind of thing? What kind of price should I expect to pay for just parts? Are they on ebay? Should I just forget this and buy a tuner instead?

I know this is a lot of questions; I appreciate any answers!!!!!

 

Moving to 3.73 isn't worth it, you're only getting a 5% change in torque multiplication. I'd go to 4.10s. I run them with street-sized tires, tow a lot, and absolutely love them.

While they're in there, you may also want to get as LSD installed. Really helps on slick boat ramps.

Unless you know what you are doing, you may want to leave this to a pro.

BTW, I've done all the typical mods over the years, the two that I wish I had done from the beginning:
Supercharger
4.10 Gears
...in that order.
In my OPINION.

Tuner will give you a bump, but going from 3.55 to 4.10 gives you a 15% increase in torque multiplication. Very, very noticeable...and much less gear-hunting on uphill grades. Plus you may not have to downshift as often to pass on the highway.

 

I think that I will check into this as long as it's not to expensive.