Group, I posted on the site the two differences in the puel pumps heads and also a problem you may encounter when changing from the long neck to the 957 with new check valve. You can see on my site: http://www.specialtauto.com/fuelsystems.htm Thanks to DMC Joe for thinking of this and letting me know. John Hervey www.specialtauto.com P.S. I you don't have his Air Bleeder Fix, summer is coming. It's great. Were getting hot here in Texas.