I rebuild my own. I have saved a bunch of cores and some old kits, that way I can be sure of what I've got. I bought a few oversize throttle shafts from Mac's and the appropriate piloted reamer so I can handle the only real wear area on them. A tip : The ball/lever on the end of the Mac's shafts is kinda' flakey. It is held on by a screw. The same part on the stock shaft is held on by the peened over shaft. It is a simple matter to grind the peening off and put the stock lever on the oversize shafts. When I use the proper power valves and gaskets, I've had pretty good luck with them. It's a lot cheaper than a new one or even a rebuild. Plus, a lot of satisfaction in doing it yourself and it's not that hard to do.