I'm looking in to these going to see what you guys think..
http://www.justrearends.com/ProductDisplay.aspx?ID=86289389-7b15-4c6e-940e-1419a3e565bc

http://www.justrearends.com/ProductDisplay.aspx?ID=36701149-3a54-42b3-b71a-0ab84264a3c7

Nice, those look really nice. I dont know a whole lot about the topic, but the second one will have you further into your powerband when you want to access it, and the first will provide better mileage, and a more even power application. Im unbiased.

Nice truck in your sig there Nomad, it looks really nice.

Thanks man she's my baby.

Personally if you are going to purchase a new third member with an LS then spend the extra money and get the True Trac LS. It is a much better unit than the OEM Trac Loc. Trac Loc's are crappy LS units and since you are going to the trouble to get a new third member then you mignt as well get a good unit. The True Trac is hell for stout. Looks like your truck is set up to spend more time on the street than off road, so unless you tow heavy in the mountains i would get the 3.70 rear end for better MPG.

Thanks man.
So this one would be the better choice for my truck..
http://www.justrearends.com/ProductDisplay.aspx?ID=081de2f0-54da-44d6-b928-d330dd9255d4

Tex,

Since you indicated you wanted a posi and not an open rear axle, yes IMO the True Trac is a much better unit than the OEM Trac Lok. Trac Lok units are not very robust and the clutch packs wear out fairly rapidly. There are no clutch packs in a Truc Trac, it uses gears instead, and is a much more robust and trouble free unit. As far as gearing, it appears your truck is set up for mostly highway use and not offroad use, so a taller gear (lower numerically) will provide better mpg and the engine will turn lower rpm's while cruising down the highway, therefore the 3.70 is a much better choice.
What gear ratio was originally installed in the truck?