Mark, the # of (dist) degrees added by the can would be stamped on the arm on it that pulls the top plate. remove the 2 screws & with a screwdriver lift up/tilt the top plate slightly to the right angle nub on the end of the arm is out of the hole in the plate so you can pull the can/arm out of the dist housing. The # is likely on the bottom side of the arm (that'd be too easy to be able to just eyeball it & not have to R&R it!). Double that # for what it will add for timing at the dampener. There are a bunch of cans available & that vac pump works good for checking that the can ain't got a leak & for the amt of vac to start it adding advance.