Hi Dan:

Good luck building your Spit! If you haven't done so, there are two reviews on the kit, both can be accessed through the Tower web site, just look up the kit and follow the links.

Regarding the retracts, the Robart retracts may be the least cost option! if you stick with pneumatic. Tower sells the Century Jet complete retracts for the kit at $208. I did not pay this much for the Robart set plus accessories. The pneumatics are not difficult to install, probably much less bothersome than mechanical ones in the long run.

The kit is also engineered for the Robats, they just drop in. If you go with another option, modifications may be required. The instruction manual also shows exactly how and provides the parts to set up your air valve link, etc. Not much can go wrong there.