The "rivet" in the pic is a "turn and lock" connection. If you take it apart you turn to release and then reassemble by inserting the new advance and when you turn it into place it locks so it won't fall off. The difference in the manual and what you have is the difference between a car advance and a truck advance. Get the straight truck advance and it will look like the manual. Now for a wild [censored] scientific guess...the GMC dizzy is the same as the Chevy dizzy. Now, if I am wrong some one help straighten me out.
