I decided to pull the "Repair Parts Manuals" for the 36 and the 36-B to see if I could add anything to this discussion. First the 36 in all my manuals have four flat panels and long strips that covered the four corners where the panels came together. Also the 36 has no sight glass in the face, it has an outside sight guage. As Dick Bennett said, it has a pipe frame and the manuals confirm that the tops are not interchangeable. All the 36-B manuals show the 36-B having panels that step down on the front and back, and these overlap the side panels. It also has a sight glass in the face. I am not saying all 36's and 36-B's are this way, I am just saying that this is what the eight different dated "Repair Parts Manuals" that I have, say.
Author, 1st & 2nd editions of Gas Pump ID book, 3rd edition is now available at
www.gaspumpbible.comAir Meter ID book also available