Any ideas where to locate a DOOR for an old TRANE UNIT?

This may be a lost cause, but I am trying to replace a door for an old TRANE AIR HANDLER and Trane is no longer able to identify the original part numbers.

Does anyone have any ideas on where I may be able to source?

TRANE

MODEL: TUDA042C433

SERIAL: M00K00187

The original unit is located in Memphis Tennessee.

I appreciate any assistance and expertise you can offer.

Chris