You mean 3.89's? Sure, great ratio...perfect for modest street performance with a taller tire.
You can check for T-loc by jacking up one wheel, with the trans in neutral, and attempting to rotate it. If you can't rotate it by hand, most likely T-loc. Be careful on truck rears as it might be 31 spline..
Prices would go all the way from 50.00 for a 3.89 28 spline open to a few hundred for a 3.89 31 spline T-loc...note, that's what I'd pay...retail might be higher..