Answer: A Type 6 Muffler body will typically be round or oval shaped. The exhaust gas travels IN through the END and OUT through the SIDE.  Both exhaust pipes are typically made with ID configurations, but there are some listed here that have OD Outlets. Sizes Range from 3.5" to 5" Pipe Sizes.

Refer to the Chart Below to ensure you are getting the correct muffler for your truck.