I've seen as many 39's without ad glass as I've seen with ad glass. I think any short 39 is common.
Some oil companies didn't specify ad glass for their dealers pumps.
About the only "farm" pump I've ever heard of is the gasboy. Farmers wouldn't have bought computing pumps. Why would a farmer buy a new pump that computed the price? Almost all farmers used old pumps that their fuel supplier loaned to them. When the new environmental regulations took effect farmers went to above ground tanks with small non-computing tank mounted pumps. That's when the bulk plant operators either gave the old pumps to the farmers for scrap, scrapped them themselves, or hauled them back to the bulk plant. That's why there were so many pumps at the bulk plants a few years ago. Chances are that if you find a pump on a farm it really belongs to the fuel dealer. Remember a bulk plant operator saying he had pumps on loan to farmers and wanted to know how to go about getting them back?
Bob
Wanted: Gas pump globes:Sinclair & affiliates, IL companies. Ripple bodies. Anything Sinclair, Stoll, Pierce, 4 Bros.
http://www.lastgas15.com/