This may well be an M-606. I wish there was a photo of the data tag or serial number. If this is truly an M-606 and its runs and drives as described, this is a good price.
https://inlandempire.craigslist.org/cto/d/rancho-cucamonga-1964-cj3b-willys-jeepm/7757491548.html
“Very rare , all original older restoration. No rust and very straight body with little to no filler. Runs and drives great. New military style seat covers. Clean title in my name on PNO. No trades”