I've gotten axles from Raxles. I haven't had any issues with them and they also lend you the tools to remove yours if you need them. You do need to send in your OEM core so make sure yours are still OEM. They are a bit more expensive then the other aftermarket new ones but they seem to last a lot longer than those.
As for skid plates there is Evolution that makes an aluminum engine skid plate. They don't make the trans skid plate.
There is also a place in Europe that sells steel engine and trans skid plates but you have the gamble of ordering from over seas (unless you are already over there).