63-66 idler arm conversion to late model thru bolt ?

There was lots of fuss back in the day over the early design needing improvement. Scott Harvey engineer for Chrysler, also a rally car driving early Barracuda was the one to get idler changed to the later design. Company by the name of Quay Norris used to make a ball bearing improved idler arm (long gone). Firm Feel makes a retrofit kit, anyone try this kit? would be interested in results.