Mobile home type furnaces usually have all the manufacturer’s clearance installations instructions on or inside the door on a plate (eg. side, front, rear, top clearances) and whether they need a special base to be installed on a combustible floor.
Did you see anything like that?
At any rate the install sounds non-typical and handymanish.
long story about this inspection but this place was a wreck… there was plenty of installation instructions, but i was curious if these units limited to mobile/manufactured only…
Furnaces for use in mobile/manufactured homes must be listed for that use but I don’t think there is a restriction for them to be used (properly installed) in mobile/manufactured homes exclusively.