Actually pretty sure. When I use the world "about" its not a specific measurement, though I pretty sure original statement is correct... If I remember correctly, the 510s came with 3 different strut lengths over their production time, but all within a close range. The number that sticks out to me is 1 3/8ths inches longer than ZX struts. Obviously if youre going to use that number for any cutting purposes I would do your own proper measurements first.
You dont have to cut them, mostly just shave the OD some. They are just a tight fit. If your struts are already shortened, thats the insert you have to run.