How many different ranking lists were there back in the 70s and 80s
And were these lists updated every week
These are tough questions to answer. The official WTA rankings debuted in 1975 and were biweekly for several years. Once they debuted, they were generally considered the primary rankings.
However, there was also something called Computennis rankings by in the mid-1970s, compiled by Jeff Sagarian (I know I've butchered his last name, but it was something like that)
As noted in this thread, Virginia Slims maintained a ranking system, but it was truly only for entry into the Virginia Slims tournaments. I think it was even separate from their points race, which was published at the conclusion of each tournament. Likewise, once the Colgate Series started in 1976/77, it also published a points race. Eventually, these two would merge, as Virginia Slims became part of the overall tour, or vice versa, depending on how you look at it.
Of course, most national associations also published their country rankings in the 1960s and 1970s and they were prestigious and often controversial as all were subjective. For example, the USTA co-ranked Jimmy Connors and Stan Smith No. 1 in 1973 -- even though Connors never lost to Smith in head-to-head and had a slightly better overall record. Regardless, until the computer rankings appeared, these national rankings were extremely important.
As you've seen in various threads, magazines and even reporters also had their own subjective rankings -- but they were usually year-end affairs.
I know it's not much, but maybe it helps clear up the confusion somewhat.