I bought a police trade S&W 5904 last spring from CDNN. THe gun was made in '89 and carried on duty. I replaced the recoil spring, something I would do with any older pistol, and changed to straight back grips.
The gun has been 100%, shot everything I ever put in it, and my regret is I didn't buy 2.
Maybe for a birthday present for myself this August.
Great pistols, all the 59's.