Have you gone to Archive of Our Own (AO3) and searched the 'Dean Winchester/ Jax Teller' tag?
SylvanWitch's "Biker 'Verse" series is there too (that's where I read it. ALL OF IT.), as is chemm80's "Body Work" series, nyxocity's "Rising Force Verse", among others..

FanFiction has a crossover called "Sons and Brothers" by Zara Zee, there're gay jokes but it's not really slash. It's also a pre-series setting for both shows, so it includes John and Sam (not Jax's dad). (It's really the only fic I like there in that crossover section, the rest is mostly about Mary-Sues.)

There's sandm1827's Sons of Anarchy/ Supernatural GIF-fic here on LJ, it's Jax/Dean, has thirteen parts so far and ones a YouTube video. (I went to YT and found a few crossover videos, as well. haha)

I, too, am on a quest to find more Jax/ Dean fic. Or just good SoA/SPN crossovers, in general. There doesn't seem to be a lot.. :T