http://www.pbreview.com/products/reviews/1335/
there is the product...i couldn't find any for sale with a quick search. i do see them occasionally here and there. i think i got rid of mine but i will look tomorrow and make sure. i have seen them on ebay before. the hard part is a lot of people dont have a clue what the part is, so the name they list it for sale might make it hard to find.
they also made them for shoebox shockers i believe. or the part also worked for shoebox shockers. although they switched the maxflo up a bit so i wouldnt count on it working both ways. my old school imp came with a maxflo that said shocker on it and it worked for me.
edit yup one on ebay:
http://www.ebay.com/itm/Vintage-Smar...em257219 7363
"vintage" haha