For the front, it depend on the diff case. If the case can hold a 10x15 bearing, you will be fine and all you will need will be the nitro diff and 2 10x15 bearings. I've had two E 4 Tecs and both had different front diff cases. Just check to see which one you have.

For the rear, you will need the tension cams that the nitro 4 Tec has. On ebay, there is a seller that sells the complete nitro diff with gears, bearings, and the cams. But that is the only other required part for the nitro diff swap.