I have converted my '39 to discs with the stock straight axle. I am also using a 2002 4WD Blazer rear axle with rear discs. I originally intended to go with 5 lug 4-3/4" bolt circle wheels, but could not find anything that would work with the stock hubcaps and look right. I sent my front and rear 5-lug rotors and the rear axles to Moser Engineering in Indiana and had them weld up and re-drill for the stock 6-lug pattern. Now I can use my stock 16" wheels with the disc brakes.