A more interesting question is how many Clinton voters who are old enough to have voted in 1984 voted for Reagan. My guess is not a majority but still a very sizable number.
We have at least two such posters here on the Atlas Forum who fit into this category: mollybecky and GeorgiaModerate. mollybecky openly stated that they voted for Reagan in 1984, and GeorgiaModerate, I'm pretty certain, was a Republican for decades before becoming an independent and subsequently, a Democrat. Conversely, we have a Trump voter here who did not vote for Reagan: Fuzzy Bear. He has said that he abstained in 1980 and voted for Mondale in 1984.
Wow I'm fairly shocked that there are three posters born in the early 60's or so! They are all older than my parents
GeorgiaModerate and Fuzzy Bear, in fact, were born in the 1950s (I don't know about mollybecky). Two of this site's moderators (muon2 and Torie), who haven't been active as much recently, were also born in the 1950s. These four Baby Boomers are probably the oldest posters on this website, which tends to skew young overall.
Iirc the oldest poster overall (though he is not all that active) is Arkansas Yankee who is like 75 or something like that (not to be confused with NC Yankee who is a radically different poster and way way younger than 75
)
But yeah they are exceptions as Atlas skews young for obvious reasons.