Ok its my turn to appoligize for my error. It was 30 yrs ago and a lot of alluminum cans. The truck I bought had a 6 cyl 4spd and the guy had put in a 289 and used the flywheel from the 6 banger.
I originally thought it was possibly the harmonic ballancer but after talking with a backyard mechanic he suggested a flywheel from a 289. I pulled the tranny & clutch, buzzed off the flywheel changed it out, I dont remember if I changed the clutch and pressure plate but when I put er all back together she ran real good. Sorry for the brainfart.
Just so you all know I think this is a great info sharing site and it has helped me to understand these little Zukes
Keep up the good work guys
Rebel