okay i am going to turn my 80 into my new off road rig. I'm planning on doing a five lug swap and upgrading the ea71 up to an ea81 and i want to upgrade to a dual range transmission. I just happen to have a neighbor that has an 87 RX with the dual range AWD center diff lock and i can get it for dirt cheap. what i am wondering is are these transmissions tough enough to stand up to bigger tires and offroading? would i be better off just getting an old dual range transmission? just for reference i am planning on running 205 75 r15