You can buy a "kit" come with buffer tube castle nut, end plate, spring , buffer and stock. Just google Around. Milspec is the most sought after size. The other one is "commercial" it's pretty much a smaller diameter tube.
Btw, where you from in ky?
And I saw heaven opened, and behold a white horse; and he that sat upon him was called Faithful and True, and in righteousness he doth judge and make war.