some folks on ebay have been listing some 19.5 dually rims from p30 step vans. they're in ohio i think. i you run into somebody who's into the 4bt cummins they'll usually know where some some p30 wheels are. the p30's are a common source for the 4bt. that's how i got my 19.5 wheels.
there's been some talk about these wheels not looking quite right on the older trucks (like my ad) because they don't have enough handholes. i've come up with a trick to get 4 more of them in the center.
won't require any special tools or machine work. when i get it done i'll take pics & submit it for a tech tip.
