I think they are both great upgrades. (balljoints and free spin kit). I've installed a few of the carli joints. They are really nice and carli is great about standing behind there products. The carli joints came out first then dynatrac copied them. I don't know any more about them.
If you are running bigger tires I would definitely look at free spin kits. Those unit bearings just don't last w bigger tires. I was helping a kid w his truck and his unit bearings last about 800 miles. But he did have 14" wide wheels w 2" spacers! :-\ I told him it was a bad idea. Lol.
Probably at work under a truck
