Posting this in case the info helps someone.

There are two "versions" of the #54558 Tamiya TT-02 Aluminum Motor Mount.

The version of the #58558 Aluminum Motor Mount that is available as a separate hop up part has 5 attachment positions per side labeled for pinions 16T-25T.

The version of the #58558 Aluminum Motor Mount that comes included with the TT-02R and TT-02RR kits also has 5 attachment positions per side, but its labeled for pinions 18T-27T when using the included high speed gear set 68T spur. It’s also machined slightly differently.

The version of the mount that comes with the R/RR kits isn’t available separately (as far as I can tell). I just happened to notice the difference when I was swapping motors between my regular TT-02 and my TT-02R (built without the highspeed gear set since its not allowed in our club’s TT-02 class).

Not sure why Tamiya chose to use the same part number, but if you have TT-02R (or RR) kit that you run with the standard 70T spur, make sure you ignore the labels on the mount and pay attention to the A-K labels on the Motor & Gear chart in the manual.