Over the years there have been very minor, even subtle changes to stock design and other things. For my money the ones made in the 1970's and 80's are my favorites. The safety was added in 1982 or 1983, so between 1972-1982
From 1972 to present you subtract the 1st 2 digits of the SN from 100 to determine year of manufacture. So anything with the 1st 2 digits 18-28 would be 1982 to 1972.
The '60s and '70s rifles have treated me well, too.
But I think quality was just as good from about '96 to '06 or so. (04 through 94 prefixes)
The cross-bolt-safety (CBS) doesn't really bother me. But I don't use it; so I generally avoid the CBS rifles, and delete the safety on those that I do end up with.
Minor correction to date stamps:
The 'code' started part way through '73.
So '72s were still stamped "72" for the serial number prefix.
And since '73 saw both dating methods, they can be found with a prefix of either "73" or "27" (100 minus 73).
The change is apocryphally attributed to being so that buyers couldn't spot NOS rifles and leave them languishing on dealers' racks in favor of a newer one.
In minor defense of Remington (I'm gagging, just typing that)...
Two of the nastiest "JM" Marlins/Glenfields that I have owned were '70 and '76 models. Terrible fit and finish, and really, really rough machining. One of them, a .30-30, even had a barrel that followed the .219 Zipper "bull barrel" contour to the rear barrel band, and then transitioned to a standard contour out to the muzzle. It should have never left the factory. (That rifle now has so many Marlin, Glenfield, and Remlin parts on it, that it is called the "Gremlin".
)
No rifle is perfect.
But it's usually easier to spot the basket cases and good rifles on the used rack, than when everything is brand new.