Diesel exhaust
Bought one from Camping World for my F-350 PSD dually, never had the exhaust problem with the fiver but did have soot on my rear fender above the pipe. I bought a chrome tip which looks pretty sharp - had to hacksaw off several inches of the tail pipe but it was not a difficult job. I think my mud flap keeps the exhaust off the trailer.
'98 Kountry Star 5th wheel
'99 F350 Lariat PSD dually