When I bought my 37, It came with an external filler neck that exited through the cab behind the passenger door. The hole that was cut looked like it could have been done at the factory but the interior trim panel & seat riser were poorly hacked to allow for the filler neck. I'm guessing mine was modified some time during it's life prior to my owning it. Mine has a 38-46 type tank. I'm still debating whether or not to keep what I have, return to under seat filling or under bed tank. So far I've been leaning toward leaving it as I bought it.
