Ok Thanks for the info.
I am trying to get this truck together as cheap as i can as it wil be a spare toy. I picked up a slighly used HPI .25 motor complete w/ pipe , roto start, clutch and bell and every thing i need to drop it right in to the truck off of eBay last night for less that $100. so once that gets here i am ready to roll.
As for the diff's i am not going to replace them till they go bad.