[AJD] 1931 Unstyled John Deere D Exaust Pipe and Seat Spring

[Kropelin]

Hello, I have just purchased a 1931 u/s D to restore and have a few questions to ask of you folks out in ciber land.
As I have undertaken a earlier project with great sucess a 1939 John Deere B many years ago I have once again been bitten to do another. 
My 1st question is: Does anyone know what the exaust pipe assy looks like as a cross section? This tractor used to have one however the past owner stated that it had fallen off in the driveway and his wife ran over it with their truck. I think that I can reproduce it if I can determine what the inside cross section looks like the J D part assy number is AD 1203 R which is the muffler D2255R and a spark arrester.
My 2nd question is does anyone know where I can find a used seat spring assy part numberAD 758 R for this tractor?

My serial number is 110xxx. Thanks Kevin (krop8913)