I was considering a disc brake conversion for My 09 4.0, 4X4, extended cad. Who makes the best kit, and do Y’all suggest it, or not?

 

I thought about doing it to make it easier to do the rear brakes when they wear out. I finally decided it was more trouble than it was worth. You don't get that much improvement in braking ability because most of the braking is done by the front brakes. The rear brake shoes are difficult to replace but they wear a very long time. I replaced mine at around 40K miles on the truck because I found shoes with a good friction compound to improve stopping ability. At 242K miles, I still have the same shoes on it and they have plenty of wear left in them.
The trouble of switching to disc brakes is a lot more work than replacing the brake shoes and you don't get much improvement in return. If you want them for looks, maybe it is worth replacing.