Thought I'd share......I sent in a sample 4500 piston into ebay seller "l'il red barn" about five months ago so this piston assy. could be made, I'm happy to say they are now available by them on ebay, he's sending me one free of charge for sending in my sample, I still have a 4500 waiting for this piston, so I'll be able to check out how well these pistons fit and work....