I invite anyone who thinks getting an STC approval is a simple process to just download this handy 96 page guide from the FAA.

https://www.faa.gov/documentLibrary/.../AC_21-40A.pdf

And, no, you can't just change the make/model on the paperwork and resubmit it. The process is the same for a different aircraft. (Pawnee vs. Cessna 185 etc.) You CAN apply for an STC within certain parameters for aircraft of a similar "family," like Cessna 180, 182, 185, but there are still differences that must be defined for each model unless the equipment, processes, installation and materials are IDENTICAL.