Answer: A Type 4 Muffler can be round or oval shaped. The exhaust gas travels IN through the SIDE and OUT through the END.  Both exhaust pipes are typically made with ID configurations. Sizes Range from 4" to 5" Pipe Sizes.  The Inlet or Outlet Offset Position is the measurement from the bottom to the top.  The clock position is used just like you would tell time. 

Our pictures shown are just a representation of the type of the mufflers we sell.  

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