Hi Mate, welcome aboard. THe Firehammer is a good unit. As you are in the US, I will leave the best place to get your spares to your local guys. CSP has got the MT version...and would be on top of that.
From my experience, the most annoying problem with the Hammer is the mesh on the pinion gear on the layshaft, to the diff gear. This can be a very unhappy union at times. Any slight gap in the mesh, and you gring out the pinion and/or diff gear......FRUSTRATING! You can go a long way to fix it by installing an alloy diff upgrade and getting alloy diff blocks.
Another common problem is shredding the spur gear. This can become worse when you put a pipe on it, or upgrade your engine. Steel spur gear solves this.
Finally, a LOT of FG parts fit the Hammer....and they can be a good idea for when the stock items break.
Again, welcome aboard mate.