I'll help u just a little bit more then I'll be done. Lol
But yeah the RS4 3 RTR has the same design as the RS4 3 EVO except without upgrades like the 2 speed, hardened diffs, and the bigger engine. Otherwise they are identical. Think of the EVO as the souped up 3rd or 4th generation of the RS4 3 (pretty sure there were 12ss and 18ss versions a while back). FYI my version came stock with the weak 15FE engine.. shudder.
Those hardened diffs can be expensive if they aren't stock! Whew! I still can't believe how much they were when I added it all up but it was a need when I upgraded to a 3.0 engine.
I got a look at the one way bearings on the 2 speed. They are in the purple hubs that hold the spur gears right? Well I looked at the shaft and it probably won't work with the spur gear I linked in my previous post. There's a ridge in the middle, no doubt to seperate the 2 gears. But I do have the part number for the single speed shaft so I will link it thru the Tower.
http://www3.towerhobbies.com/cgi-bin...&FVSEARCH=a832
You will be able to reuse the output cups and the outer bearings (HPI #B030) slide onto the ends of the spur gear. I'm not sure how much the shipping would be (I see u live in Australia) or if u can find these parts locally but its like $12 for the parts themselves and you will have reverse.
Overall this is a great idea. I think I might have to do this down the road once I have some spending money.