Correction... 5:1 use to be stock a LONG time ago. 6:1 low profile has been the go since the early 80's.
There are dozens of boats around here from the early 80's. In our little "yacht club" we have a '79, two '82's and an '84. Before we upgraded the early boats all had two hangers on the boom with single blocks. The '84 had a double upper but was still 5:1.
Which brings up another question....how far back on the boom is the block hanger on the newer boats? Not sure which of my two block hangers I should be using for a triple upper. Due to the takeoff angle, one works better from the tramp and the other better from the trapeze. Maybe I should put another hanger right in between.