How do you guys flare aluminum fuel line to attach AN sleeve and fitting? I believe it is 37 degrees.

you need to use a 37 deg flare tool

Who sells them?

I bought a 37 degree flaring tool from Parker hydraulic company, not cheap but it does work excellent I have heard of some racers using a 45 degree flaring tool and not flaring the line out all the way to 45 degrees, they would quit at about 30 degrees, they then used the tubing nut and the male end of the other fitting to finish the seating of the line. That will probally work fine on soft aluminum lines but not worth a hoot on hard drawn aluminum tubing ,stainless or regular steel lines

I got a cheap 1 from summit that works just fine

Or you could go with a compression fitting to AN.
Or you use the standard flair kit but when you use
the double flair button you dont press it all the way
down leaving a much shallower flair... works well

I used the compresion style tube end adapters from summit. They work great.

Rigid makes a very nice tool. That is the one I use. Slide on a tube nut and a sleeve, flare and you are done. Their tool makes awesome flares.

ALL my FUEL and TRANS hard lines on my car are aluminum.

Watch the connections on aluminum tubing when using compression type fittings. They have a tendency over time to crack the tubing around the ferrules.The compression ring can act like a saw and eventually cut into the tubing. Something to be aware of. A flared fitting in my opinion is much better and safer in a race car.

This is the one I use. I like it because it "ROLLS" the flare into the tube.

http://www.toolup.com/ridgid/41162.html#

Ordered one of those last week . Will be on my porch tomorrow!

I turned a 37 degree button on my lathe and used that with my regular flaring tools.