Yeah you can reuse your stock cross pin. My D30 lock right came with a new high strength cross pin but cost a bit more than 200 Dollars. You can always buy a brand new stock cross pin and use that if your current diff has a bunch of miles on it.

You don't really need instructions perse it's a pretty simple install. If you were in San Diego I'd invite you over to the base hobby shop and we could have it in the Jeep before lunch.