Lets not forget the 67 idler arm is different as the 67 k-frame has a single mount point while the 68-up has the idler sandwiched between two mounts. Everything will interchange if you use the correct early or later parts in combination.

The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.

JB Rhinehart, Realist

A-Body's RULE!