Anybody no what size the original positive cable is on the 7.3 idi The terrminals on the cable is starting to split open on mine Thanks

 

I think it's 2/0 from the factory I made mine out of 3/0 That's about the largest you can run on these and still make the bends.

 

factory is 2/0,but sometime around the late 80's (and back from '83.so like '83-86 - my guess is this followed the 7th generation and stopped with them,but not sure) they used to use 2/0 but a hunk of 3/0 going down to the starter from the pass side bat.this is really only a good idea if you see temps of 0 degree's or less often,otherwise it's not going to do ya much good.
that said,like RLDSL,i also used 3/0 cable.i used it for all 4 pieces.