I ran an old Australian Muscle Parts belt drive. I felt like I was the R&D guy for him. I finally quit emailing and just made it work. Would like to see his come back just for some competition. As for the idler it is on ALL the raised cam BB Mopar Jesel. If you are patient they can be located from time to time, I will warn you if you buy a used one and it needs a belt or seals may as well buy new. They are quite proud of their stuff