Stop in for a cup of coffee

brewers shows the clutch fork as 12.5 inches overall length for a 68-76 A- body with a V8

they don't sell one for a slant six ....soo I need to figure out what is the overall length for 68-76 A-body with a slant six.

I have the 12.5 inch one in there now and I am suspecting its the wrong one for a slant with a 3 speed.