For those with a missing heater motor here is a simple solution using a 4” bildge blower fan. Two options: Budget and Professional attached are pictures of both versions.
Option 1: Cut away the housing and slide into tube. While this does work, the fit is tight. My only concern going this route is the it vibrating and wedging against the housing. You could also use the 3” version.
Option 2: I made a custom housing that again I’d be glad to post or send the cad files for someone that wants to have some or one made. I used a Rapid Prototyping Process called a FDM machine but a SLS would work great as well. If enough people expressed an intrest I would consider coordinating getting some made. How much? I don't know for such but they won't be cheap. (I had my built via the barter system. Trading Cad skills for parts.)
I never had a original fan so I don’t know how it compares. But its quite, and blows 235 cubic feet of hot air per minute at your feet.. Hook inline with a 7amp fuse and your legs will be on fire.
Standard fan can be bought online.
Contact me directly for the cad files for the heater housing. These files are for educational purposes only to show what worked for me. While they worked for me I take no responsibility for what you do with them. Should you decide to do something similar I’d advise you to double check the sizes so that the dimensions are correct for your setup. The Cad files are smart so they can easily be changed for your application.