Differential Gear Set Installation

[tomfg]

I see that LMC (and maybe others) list "ring and pinion" sets for sale.
I need to do something to make my truck more pleasurable to drive, and improve the gas mileage I'm guessing....... hasn't been on the road long enough to check the MPG's yet.

Has anyone had any experience with the aftermarket gear sets?
Would be interesting in hearing about their quality, problems of
installation, and how it "turned out", i.e., "GREAT", "It whines
worse than my wife", etc.
I'm assuming that they're not made in China.... or they?

I haven't had a differential apart for 30 years, other than pulling
an axel, etc., but assume I could do the job if I find the right
manual, and figure out the pre-load, etc.

Thoughts welcomed, thanks, Tom