I found out that the diamond grips were banned in 1968 by the AFT with the 1968 Gun Control Act.
Welcome aboard from ol' Wyo.
Whoever said what you "found out" was either jerking your chain
or should write fantasy novels.
Smith & Wesson issued Engineering Change order No. 944 to
eliminate the diamond on most stocks on January 11, 1966. It
took more than two years for the company to exhaust its
diamond stock inventory for most models.
If you remove your stocks you should find a serial number
stamped on the inside of the right one. If it matches the serial
number on the butt, that's a big plus.
Based on others that bracket yours in the database, Smith &
Wesson likely shipped your Chiefs Special in spring 1967. The
Model 60 serial range demkofour mentions usually shipped much
later than the Model 36s in the nearby range.
Also, Smith & Wesson calls the hinge that holds the cylinder the
yoke, not the crane (that's the term used by the four-letter
company beginning with a C) so the MOD. 36 stamp is on the
frame in the
yoke cut.