JDJIM
Guest
If they are same as 40 series heads 24 driver and 30 driven is the standard . Don't know if they are the same though . I use a 643 on a CIH 1660 since it has NO VARIABlE SPEED which I sure miss from my old 7700 I use a 28 0r 30 driver and the standard 30 on the driven . Also have a 26 driver. The 26 and 28 are off of IH 800 heads , same size shaft just had to grind the inside off a little . JIM