I hope I am posting correctly, first time.

I assist a small private school in Northern California with their site needs. We have a classroom which is a 3 piece manufactured building from about 1969. Late last spring a strong smell of natural gas was noted and our HVAC professional found a burnt out heat exchanger. Problem is the unit was painted the year before and all the data blocks are illegible. I did peel off one and was able to read Coleman, backwards, from the back. Our professional's parts supplier has not been able to help. I am posting these photos in the hopes that someone can identify this model. This is heat only. The A/C is mounted below the heater. Thanks.