69 772 fan and clutch

[Rixls6]

I have a fan and clutch assembly dated July of 69.
Is the clutch specific to certain RPO engines?

http://i36.photobucket.com/albums/e43/Rixls6/th_69Z28Clutchfan009.jpg (http://s36.photobucket.com/albums/e43/Rixls6/?action=view&current=69Z28Clutchfan009.jpg)
http://i36.photobucket.com/albums/e43/Rixls6/th_69Z28Clutchfan007.jpg (http://s36.photobucket.com/albums/e43/Rixls6/?action=view&current=69Z28Clutchfan007.jpg)
http://i36.photobucket.com/albums/e43/Rixls6/th_69Z28Clutchfan003.jpg (http://s36.photobucket.com/albums/e43/Rixls6/?action=view&current=69Z28Clutchfan003.jpg)

[Steve Shauger]

The cluch was specific to it application. For instance the clutch shaft length was different on BB vs SB, in addition RPM operating range called out different clutches. For instance a Z28 had a different clutch than a 307 with A/C due to rpm range. The same applied to solid lifter L78 vs L35 w/C60,K02.

[Rixls6]

Thanks Steve.
What clutch shaft length would be correct for a 69 big block, and what would a small block be?