All the M38's with the artic top kits that I have seen use a windshield frame with no pivot points. The windshield frame mounts vertical and bolts to the side of the body. I can't tell from your photo, but does your windshield frame have pivot arms?
That IS very unusual! I agree that the frame is M38, appears to even have the rifle rack brackets, but there is no indication that the wipers were ever mounted in the normal location. I think you should post a photo on the M38 forum on the G503 board and see if somebody can identify it. Possibly something off of a foreign-contract M38?? Would be interesting to know.
Tony, I've not seen an M38 w/s with wipers in that location. I'm guessing its an M38 because of the bolts above and below the vent. Perhaps others may have more insight on why you'd have manual wipers like that - could be how aftermarket w/s frames come. Kind of unique. If you choose to go powered on your wipers, that might be a good place to mount them.
Attached is a windscreen we purchased from a locally in New Zealand as our CJ3A has a badly home-fabricate windscreen frame. I am not sure what it is from, maybe a M38? but the windscreen wipers are manual and on the top. Any ideas out there? Sorry for the bad photo, it is sitting in the back of my parts shed.