New to e-maxx conversion

Hello guys, i just buy a 3905 e-maxx for $100.00. The truck have the traxxas center steel drive shaft on it and i want to put my MMM/2200 combo in it and run it on 5s.
I want to keep it as stock as possible.
But i would like to put 1/8 buggy diffs on it, so i plan to order this bulckhead.
http://www.rc-monster.com/proddetail...LM18700&cat=47

Just want to know if, for this price, i would get both (front and rear) or the price is just for one?

And please, if somebody could tell me if the tranny is solid enough for brushless power on the new 3905 e-maxx or should i upgrade it?

And for the motor mount, could i keep the stock one and mount my Neu 1515 on it, or should i get a single motor mount plate?

Thank you?

David