How to identify a 67 specific k-member

You could modify it to be "like" the 68/ later, but you'd about need a sample K for a pattern. Idlers are no joke ==they must be proper geometry or it won't handle "right". (Well it might go left LOL)
Ha. Ya forgot about that. Everything is so rack and pinion any more. Plus I'm out of the loop. Hit the brakes and it veers left? Needs an idler arm.