That's actually the stock RCR spur. As far as I know, without MAJOR modifications, the RCR spur is the only one that will work. It has a unique mounting process, and the smaller aluminum gear next to it comes with the spur, so they're both changed at the same time. Unless you come across a steel spur somewhere, all spurs are made out of the same material (nylon), and will last the same amount of time. It depends mainly on your gear mesh. If it's too loose, your teeth will strip off like crazy. Too tight will cause binding and something will eventually get messed up. With a strip of notebook paper between the CB and spur, slide the engine (clutchbell) against the spur, not too tight, but pretty snug, and tighten down the engine bolts, with locktite of course. Your vehicle should roll smoothly across the table/floor without binding or making clicking noises.

As far as the clutchbell (CB), there are problems with the stock RCRs. They are generally out-of-round, which will prematurely wear the spur unevenly. The other thing is that the RCR CBs are aluminum, as well as the clutch shoes inside the bell. Aluminum against aluminum isn't good. That's why if you go with a HARDENED STEEL CB, you will have a much more reliable vehicle. Make sure when you replace your CB to get the HPI HARDENED STEEL one for the HPI Savage.

There are 3 CBs to choose from - a regular steel one, which is supposedly worse than the stock one, a hardened steel one which is what you want, and a racing one, which is hardened as well, but vented on the end to allow cooling. The racing one is like $15, the hardened one is like $11 and the cheap one is like $6. I would have gotten the racing one if I had to order it, but my LHS had the regular hardened 18t in stock.

Examples:
DON'T get this one - http://www2.towerhobbies.com/cgi-bin...?&I=LXBTB3&P=7
DO get this one - http://www2.towerhobbies.com/cgi-bin...?&I=LXFKM8&P=7
DO get this one - http://www2.towerhobbies.com/cgi-bin...?&I=LXLSU0&P=7