i have the slash and am trying to get it to work with a airtronics mx3 radio, do i just have to replace the receiver to the right one, or will i have to replace other stuff. and will it even work

All you have to do is replace the old reciever with the new airtronics reciever that came with the mx3 kit. Check and make sure that the crystal is in both the transmiter and the reciever. Then your rllin