67 A body BB K-Frame vs 68-69A body BB K-Frame difference?

67 idler arm is expensive and hard to find, one year only. If you have a 67 K, I would fab the mount whatever you have to do to convert to the 68/ later idler arm
why doesn't someone make a conversion kit for the earlier K frame? Seems like that could be an opportunity for some fabricator. Maybe Mike Schumacher?