Acquired another F body slave cylinder, a new one, same part number as above.
Extended. 3.415"
Compressed. 2.530"
Why the used F Body CSC I had wasn't compressing all the way, I don't know. This GM one should give me plenty of travel with the DYAD and is nearly the same compressed as the Mustang CSC.
I thought it was important to update the post here, ya know, posterity and such.