Not sure what anyone ever came up with as a production figure for those, it was probably fewer than ten total. The FBI never confirmed nor denied having had any, then again they had a couple of Buick Grand Nationals later on and did the same. I don't think any police department was ever known to have had one.
And there were no factory Hemi station wagons. A member of the Ramchargers dropped one into his family car (a '65 Dodge 880 wagon), the first 426 Hemi on the streets by several months. There was a Modified Production Hemi wagon, a later owner tried to hype it as a factory build until the guy who converted it (from a 318 car) chimed in...
--Mark