Yea, its a flowmaster 2 in 2 out. came with the truck. lol. - - - Updated - - - the P.O. mentioned that his mechanic thought it was the chain. i got to researching and discovered the old pump rub issue. sounded like two logical explanations to me, but i don't know this guy, much less his mechanic( God bless Craigslist) Im going to have to pull the case to fix whatever's wrong so i may as well fix it all at once.