Just in case you can use it, years ago I compiled a list from everything I could find online as to major doubled dies, rotated dies, known clashes, etc. I am posting here for you.
BTW, I know clashes can, and possibly do happen for a lot of dates, however, the ones listed are noted for a lot of them. The 83 has been found with very deep clashing.
Kennedy half dollar Roll Searching Checklsit
Compiled by Earle42 coincommunity.com
Date: ...RPM..DDO..No FG..Clashed Die..Rotated Die
1971-D: ..RPM..DDO........Clashed Die..Rotated Die
1972:........DDO
1972-D: ............No FG..Clashed Die
1973-D:..RPM..DDO......Clashed Die
1974-D:.....DDO..No FG..Clashed Die
1977-D:.....DDO.......Clashed Die
1982: .............No FG
1983: .............No FG..Clashed Die
1984-D:..RPM
1988:: ............No FG.........Rotated Die
1989:............No FG**
1989-D:..RPM
- Note the No FG examples, except for the 1982, are just die polshing events that can, and do occur for other dates as well.
- Former PCGS president Ron Guth "discovered" yhe 1972D No FG and therefore PCGS decided to slab them. Other companies followed. Therefore a market was created for this date. Polishing events have removed the initials from other dates as well (I personally have found a 1989, and a 1974). These should have no extra value being it was only the company hype that elevated the 1972-D into a collectable item.
The above list is a compilation off various lists found online after being verified with pictures or actual coins.
rotateddies.com lists the following:
1965 (100#730; and 180#730;), 1967(137#730;, 170#730;, and 176#730;), 1972-S (180#730;), 1973-D (120#730;), 1973-S(180#730;), 1979-D (178#730;), 1984-D (180#730;), 1984-S (180#730;), 1984-S (180#730;), 1988-P (180#730;)
Not listed at that website: 1971-D and 1983-S.
Straight FG (type I), and flarged FG (type II):
1964 P&D, proof 1964-D, proof 1968-D 1969-D, 1970-D.
Please also see the essay in my signature concerning No FG
Kennedy halves.