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Hi, i have a set that my great grandfather bought from the mint that has the 4 varieties in a clear plastic case, in the original mailing envelope, post marked 1967, i looked around online but i don't see it so far,
were there many of these made ?
i can provide pics if that helps.

I assume that you are talking about the Silver Dollar varieties (there are actually 5). Sounds to me like it may be
an aftermarket set as I don't know of any variety set being released by the RCMs plus they did not use clear plastic cases back then. Pictures would be a great help to determine what you have.

quick pics, of what it is,

I thought that may be the set. That is an aftermarket set in a Capitol coin holder. There are some for sale on eBay in fact there is one with all 5 varieties. I don't believe they are PL Dollars but Business Strikes. If it was assembled by the RCM, it would have their logo on it somewhere.
I have no explanation for the RCM envelope but why would they ship something out two years after the coins were minted?

i don't know, but it fits perfectly in the envelope.
it was addressed to my great uncle (not my great grandfather as i mistakenly said at first) who i inherited the collection from, so he is not around to ask....

also, he had boxes of PL dollars and sets starting from 1962.

this kind of set isnt that rare. first time I saw the same thing was back in 2003-04 and it was 1 cent coins varieties set