UPDATE:
Courtesy lived up to their name and agreed to get me the right part or refund my money. VERY good customer service from David from courtesy. They are a class act in admitting a mistake and tried to do everything to make amends.
Well I ordered that rockauto part, and low and behold, it came as a silver beck/arnley part (read cheap crap). Nothing at all like was pictured online...so you cannot always trust rock auto to send you the part pictured, they do cheat at times.
I decided since the slave they sent me, although it looked and felt cheap as hell, I would install it. After all it did have a threaded pushrod ( 3/4" too long and the hemisphere that pushed was 2x as big as the OEM one), and an eyelet for the spring.
I first noticed that when I installed it it sat crooked. The bolt spacing did not allow the slave to push at 90° to the clutch fork. IF that did not suck bad enough, the flexible rubber hose would not seat properly against the slave body....what do I mean by that.. lets me try to explain it..
look at the red plug in this picture on the nabco slave. If you look carefully around the red plug you can see a round recessed relief cut into it a few thousands deep. This is to provide a good sealing surface. The fitting on the rubber hose that screws into this is completely flat..the top left of this picture is the end that goes into the slave.
The threads on that fitting go all the way down to a flat land where the hex nut is. It is one piece and is meant to sit flat against the machine piece on the slave.
Well my beck/arnley slave has a recess MANY thousands deep and the flat on the rubber line fitting cannot come into contact with the sealing surface.. so it leaks.
So now i have 2 slaves, that do not fit or are the wrong part, and I have to ship them both back...
I am going to give courtesy a call today and see if they can let me know what part I would get if they sent me a 71 slave...