Ours
had the fan up above, it had it's own covered heating element, so was true convection as well.
I have read (but never seen) that the ones with the fan in the back were from a different firm.
This oven was fully programmable, you could order several steps, using various heat forms (or together) in a row, with pauses inbetween. Worked a charm, but, gosh oh golly gee - very hard to keep the probe from breaking the cable at the plug. We went through 20 or more - one a year - and I am still on the original for the Amana RadarRange folks here helped me fix up a while make.
The important thing is that the stainless steel shelf be there as well as the 50 pound white ceramic (it might have been glass-ceramic) glass plate for the bottom.
You'll need an instruction manual, believe me.
Oh, and, yup, it's me. I'm teaching six additional classes this semester to pay my colleagues back for their help these last years. Not much time or muse - but I do miss this forum and you folks. There are several summer projects lined up for us including two MixMasters from the mixed-up pre-war era and and a 3C with stainless steel bowl and a capacitor shorted to ground. That'll all be in June or so!