37 is AN, 45 is about everything else. Im using 45 fittings. If they say a 45 will split a stainless line, I got proof my 3/8 didnt. Its weird that a single flare tool would use a 45 cone when all single flares are 37? all doubles are 45? http://www.fedhillusa.com/webnuts/common%20flares6.pdf Heck I thought the stuff was aluminum when I started working in it. Caddy Northstar fuel rail. http://www.fedhillusa.com/webnuts/common flares6.pdf
