I HATE 9Ball parts. Hate them, with a passion....pretty much every single 9Ball parts I've had broke. So I avoid them(except their hopup rubber, and now their plastic BBU for Hi-Capa, but I haven't put enough round through it yet, I am sure it'll break next time I shoot CAPS, in the middle of the COF) At any rate, Instead of that, I'd use something like this:
http://www.dentrinityshop.com/pr_details.jsp?pid=16000
Again, 2 piece guide rod, and then you can machine your own buffer out of some kind of durable plastic. Thats my plan anyway....
Things about 9Ball is that they are still a Japan brand, their parts are still made with duster in mind...