Now tell us what the gas mileage was on that thing. (especially with that GMC engine)
The factory mufflers were straight thru. My 478 V-6 had dual straight thru's from the factory. Sure sounded sweet.I remember hearing them called "chugger motors" because of how they sounded. Careful pulling spark plugs- they point straight up and its easy for debris to fall into the cylinder with the plugs out.