I had that on a brand freaking new set,of out of the box EQ heads, no less, on my Durango, it's a 360 too (magnum though) a couple of hours on a freshly built bottom end, (break in time) and it's maiden voyage was 6 miles about the last 2-1/2 on the end of a tow strap. Stuck and bent #4 exhaust. Machine shop said the intakes all had to be hammer and punched to get them out.