I've never seen a hole that shape.
Maybe it's a later model thing,but my 50 just has a circular hole at the lowest point in the truck floor under the seat,like you say I imagine it's for drainage,but why the unusual shape in yours...?
I stuck a grommet in mine.
Personally I would seal it as you also don't want any exhaust fumes etc to enter the cab from the underside.
Let's hope you don't ever need it as a drain!
Last edited by jockbolter50; 11/09/2011 9:15 AM.
