Where can I find a natural to lp converter for amana furnace

Only from an Amana dealer-order it by model number. It should consist of a few tiny parts (spring, etc) that are installed into the gas valve of the unit. I believe Amana is now produced by Goodman (Janitrol).

Asking this question, you would best be served by calling a licensed professional, as testing/adjusting gas pressures is mandatory when converting from natural to lp or vice versa, and a slight mistake in this area can be deadly.