[51504bat]

Not exactly sure what you're asking. I'm using narrow belt Merc pumps with the U shaped spacer on the 8ba in my '39 p/u. But if you want narrow belts on 8rt truck pumps so you don't need the spacer they don't exist as far as I know. You might be able to swap the wide pulleys on the 8rt truck pumps with narrow pulleys from 8ba car pumps. This would give you narrow belts BUT I have no idea if the pulleys will interchange and if they would not sure how the belts would line up. You might contact Skip Haney in Florida. If anyone would know I'm guessing he would.