Hello, just picked up a beat j5, has nice looking sprockets and brake bands, decent tracks, needs a few idler tires, has a 230/250 Chevy, I'll try to post some pics soon, ordered a new ignition for it as I think that's why it got parked. Can someone tell me what size bolt for the diff drain? Looks like plugs been missing for awhile and I'd like to run a tap in there