Sorry about that brain cramp. It's CRC or
Close
Range
Correction. By the serial number your lens (1972-March1975) is indeed a CRC lens as it was introduced in 1968. Pop the lens off the camera and look at the rear element while moving the focus to minimum distance.Towards the end of the focus range the rear element will move outward towards the mirror. This is what allows the short close focus,
almost macro minimum distance.
To chip the lens you'll need to remove the rear baffle and machine room on this lens. The chip can be bought on
eBay for $30 or so. It's programmed for focal length and f stop using a Nikon Digital camera. Look around online or
these guys can do it for you if you're not comfortable doing that kind of modification.
You can use the lens on an
F5 IF IT'S HAD AN Ai CONVERSION. I strees that because mounting a pre AI lens on the F5 will break the aperture coupling. But if the lens fits the FM2n w/o breaking anything (the little protrusion for aperture) it should fit the F5 as well. Only modes usable will be full manual and aperture priority. Metering is limited to center weighted or spot.