To lessen any possibility of exhaust fumes working up into the body, long muffler pipes in- stead of short pipes are now used under the majority of “AA” commercial types.

Fig. 1157 shows the different muffler pipe assemblies and attaching parts used oh all truck chassis.

Adapter AA-5257-B is now used with the

A-5256-C bracket on the 131 1⁄2 WB chassis with short tail pipe (see Fig. 1159). This adapter re- places AA-5257-A. It is more flexible and lessens any possibility of strain being directed to the manifold when traveling over exceptionally rough roads.

When installing a long tail pipe on an old 131 1⁄2 or 157 WB frame, new bracket holes must be drilled in the cross member and side member.