need to buy this but confused!

[captainlip]

I need to buy one of these as ive just snapped mine.....

http://www.team-durango.com/part-inf...artNo=TD330004

but it says i can only use it with these....

http://www.team-durango.com/part-inf...artNo=TD330037

why is this? i dont see why i would need it?

also what other major weak parts are there on the 410r

thanks.