how many years did abc sir day time reuns on Happy days four?

how many years did abc sir day time reuns on Happy days four?
I think from S2-S6 during the 70s till it went into syndication in 1979. I was in the 2nd grade when H Days first came into local syndication. I remember when it was hard to imagine, and I felt the same way about the Brady Bunch the year before that when it first came into syndication in c1978.

I DO remember Happy Days being on ABC every Tuesday night at 8pm
https://www.youtube.com/watch?v=tWWaAZcYaWA

https://www.youtube.com/watch?v=oQxK5VPcyUY
but am not old enough to remember The Brady Bunch being on ABC. I have only ever seen it in re-runs.