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9.0 Exhaust system

Three exhaust system variations were used in GPW production as described below. The GPW front exhaust (header) pipe used a steel flange welded to the pipe at the exhaust manifold output, Willys front pipes used a cast iron flange.

Early, round: Start of production thru July 1942. Muffler was round, otherwise the exhaust system was similar to the most common “middle” production.

Middle, Oval: Mid July 1942 thru mid 1945. Oval muffler with rolled, crimped seams (not welded). Exhaust tailpipe was integral with muffler, not a separate piece.

Late, Deep-mud: Mid 1945 thru end of production*. Muffler was relocated to the rear of the vehicle. Muffler axis was parallel to axle.

* “Ord dept report”, AAW #2 P223 states change as 7/20/44. Richard Grace states that the MB changeover was MB 401550 (late 12/44). Early 1945 may be a more appropriate date.

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Updates to this info below this line

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