GPW Deep Mud Exhaust

This Dallas-built late war GPW has a deep mud exhaust system. This system runs the exhaust pipe down the driver’s side of the inner frame rail, then across the rear frame, under the rear seat, with a muffler directly in front of the rear cross member, and exhaust exiting under the right rear of the vehicle. No more exhaust spilling out right under the passenger, and the muffler is tucked up inside the frame rather than hanging down low in the mud and snow. Some folks complain that at high speed, the exhaust is sucked back up and over the rear, but I’ve never experienced that happening.

This system came onto the MB production line in very late December 1944 and began production in GPWs around the first week of June, 1945. Given that 270351’s DOD is 6/1/45, it may have been one of the first GPWs with the deep mud exhaust. It would also appear that some Ford factories continued to use up old stock and never actually converted before shutting down wartime production.

Here’s a good summary article on the deep mud exhaust. Deep Mud Exhaust

I got my deep mud system from Army Jeep Parts about five years ago. Here’s the attachment hardware. Some of these clamps are original WW2, and some are repros.

The muffler still had remnants of Chinese green paint, most of which has burned off. I took a wire wheel to the muffler and piping to clean it up, then used matte silver VHT paint. It too will likely burn off, but will still leave some anti-rust protection.  Here’s the exhaust system mocked up. The engineering and fitment of this system are superb. The exhaust outlet curves down and rearward, coming within an inch of the inner frame rail and crossmember.