Definitely not a rat rod from the little you've shown of it...........................rats are usually field rough and rusty in appearance..........as in "ratty". This term gained some unjustified traction a decade or so ago and has faded mostly except in some limited circles.

A bit confused on you tank commentary. The picture shows a steel tank, but you mention a polyethylene tank. We talking two different tanks here? Some, most (?) newer tanks have a rollover check valve/ball in the pickup tube, could it be that portion of the pickup is installe incorrectly?