I have a 2003 boatmate trailer with a fulton jack. It looks like I need a bolt-through 1000 lb swivel fulton XP something or other, there's an XP10, XP10W, XP10L, and XP100. Does anyone know which one is correct. Some also have different snap lock holes at 1/2" vs. 3/8". I'd like to replace it with the closest one w/o dirlling larger holes if possible.

Yeah, my Fulton jack just broke (sat) on my 04 Extreme Trailer. So I'm looking to solve this same problem as well. On my trailer, the Jack base is welded to the trailer, so I have to match it at the swivel.

My base is welded to the trailer too. I've talked to my dealer, he shows the XP100 for my replacement and you just use the jack but not the trailer mounting piece. Having said that, he said it was like $80, I bought one from West Marine (via website) shipped from CA to VA, it just arrived. Also, I bought a special wrench with about a 1" recessed head with 3/4 and 7/8 to remove the old jack. I'm pretty sure a socket wrench wouldn't fit and a regular wrench wouldn't work either.