I measured the standard release bearing position, both fully engaged and disengaged, then tried to place the hydraulic bearing position as close as possible. Then it was a matter of trial and error to get the thickness spot on.
You are right about the dust cover with spring, but if you get everything spot on, it works well on. If you dont use the dust seal, you are risking scoring the telescopic bores over a period of time.
And yes, as you can probably tell, this is the saab unit also.