The conversion kits are really good quality & you will probably have enough spares to make up a 2wd for sale to pay for the kit. Thats the way I did it only not got round to building the 2wd for sale yet!!
Glad it all went well Ben. It may well be the flex in the rear arm that fecked the gear. I have the lexan cover over mine and you can see where its been battered by the top arm but with the cover being smooth it doesn't damage the gear. If you run on grass you will be fine with the cover but running on gravel can trap the stuff in there & strip the plastic gear anyway. All metal gears are noisey!!