My 3906 Mutation

[redshift]

thzero, if you're not looking to make a career out of it, there is a vast amount of info online, way more than enough to get you started!

Jpop, I failed to mention that gearing with my 3906 is not of much use for your 3905 as they are different transmissions. I think my bud is running 22/62, same 9XL 4S setup. It's good for 35ish, as is mine. In answer to your PM question, a spool simply replaces the diff cup for a posi rear end, Traxxas part # 5381X for yours. It's sold as a Revo spool, but those use the same diffs as the 3905 Maxx. If you're looking for the ultimate winter traction, then you can do front and rear. Just be warned it'll steer weird!