I went with al trans case and diff cases since i'm running a 21 kit. I was getting quite a bit of chassis flex. With the al trans case, it's pretty much nonexistant now. Same with the diffs. When your cranking 2hp at the diffs, it tends to twist and contort the plastic cases, which screws gear mesh and strips gears. I'd rather have the extra weight and drive, than lose 1/2lb and be rebuilding crap more often.
Mine is strictly bashing. I have a racetrack near me, but only one and they only like you running 1/8 buggies there. So, i spend all my time at construction sites or skate parks seeing how high i can fly.
Aluminum can get pricey and make a truck look like its for show, but when you put aluminum in certain places, it makes it stronger.
I personaly wouldn't run aluminum arms. I like having something give that's relativly cheap and easy to fix.
I think you posted the same time i did. I didn't see your response.
ACNCM bulks don't work well on the XTM chassis kit. They have the rear diff collar holes to high which in turn makes your rear center axle rub on the actual chassis or engine mount boltheads due to the fact that there is less of an angle.
The ones in the front were fine though. I run ACNCM bulks, but i had to mod the rear ones. I had to dremel the collar holes down about 6mm in order to get it to fit right. I emailed them and they said that they weren't designed for the 21 kits, just stock. But they were more than happy for me to ship them back with instructions on what i wanted. I didn't feel like shipping. So i dremeled.
The proline kit can be found here. I've bought a lot from these guys. Quick with processing an order. From order to receiving it is usually 4-5 days.
http://www.lightninghobby.com/store/viewitem.asp?idproduct=9408