If my mind does not fail me (which it has sometimes), stockers are 1.6 ratio. Sharp did some testing, and found that, because they bend, they are more like 1.5XX (don't remember the exact ratio, but it was mid fifties I think). I use Yella Terra 1.6, which are true 1.6 (much stronger than the stockers, plus rollers on them). Sharp installed 1.7's (also rollers, and also stronger), but he had to modify the pushrods for it to work.