I know very little about them. I have the McCullouch sheets for modifying them for blowers. I know they are bigger but thats it. Suede57 has built a few give him a shout. Chuck
They're bigger, but still only around 350-380 cfm. Many of the parts from the std 4000 kit will work. You can still buy rebuild kits, I found one a couple years back on eBay.