Sealant Between Dually Wheel Wells and Bed

[lgvl]

So I dropped my truck off waaay back in April to get some rust spots fixed and painted. Needless to say the schedule got blown to pieces for various autobody tech related "health" reasons, anyway it's finally been primed and he's about to spray it with poly. I'm starting to think about the seal between the rear dually wheel wells and the bed, i'm assuming some good silicone between the two to keep out water is the right way to go but i was hoping people may have the official best practice for keeping out the rain. If anyone has some words of wisdom on what to use i would appreciate it, thanks!

-Ryan

P.S.- Will post some pics when she's all done.