Looked through my Six series manuals and found these dates: E4/40/1-79, E5/80/1-80, KE&E-12-81
I have manuals that the title says:
Security Six
Speed Six
Police Service Six
and the bottom right markings begin with an E.
Then there are Titles (with over lapping dates of the "E" manuals) that say:
Stainless Steel
Security Six
Speed Six
Police Service Six
and the bottom right starts with a KE.
Then there are Titles with:
Security Six
Speed Six
Police Service Six
and the bottom right says KE&E.
In these cases the one with:
"E" are for blued models,
"KE" for stainless models,
"KE&E" (which are dated 1981 and later) Looks like Ruger just made one manual for both blued and stainless.
I could not find an "E" 81 or a "KE" 80 that was marked Stainless Steel
Me, I'm looking for manuals with 71, 72, and 73 on the markings on the bottom right, I have manuals from 70 and 74 to 86. Since I cannot find that Ruger made any major changes from 1986 until the end of production in 1988, I believe that the 1986 manuls were used until the end. If anyone has a Six series manual dated 1987 or 1988 I'd like to know so I can hunt for them.