For those of you wondering, "Why would anyone want to revert 'back' to six-lug in the first place?", then the following article might not be for you. However, for anyone with an IFS-equipped early GM pickup that you'd like to run similar-era (six-lug) wheels on, keep reading!
Up until now, in order to run '30s-50s six-lug wheels-namely the 15- and 16-inch accessory artilleries-on trucks with Mustang II frontends, you either had to have a brake kit custom-made, your brake rotors re-drilled, or run billet wheel adapters. The last two options leave too much room for error (lack of sufficient surface area on the rotors to accommodate the 6x5.5 pattern for one), and it'll cost you a pretty penny to have a set of brakes made. Thanks to CPP, none of that matters any more. Their new six-lug MII kit is not only affordable, but as you're about to see, offers "more" brake than the standard 11-inch GM rotors that most aftermarket IFS units use-and still fits inside an OE 16x4 wheel (there may be some variance between original wheels) without requiring any modifications, such as grinding down the rivets that hold the wheel center to the rim hoop.
From the beginning, I'd intended on running six-luggers on my '39, so I had Currie Enterprises do the axles in the 9-inch rearend with a 6x5.5 lug pattern. Since the truck wouldn't be on the road any time soon, I wasn't in a hurry to address the front brakes. But at the same time, I didn't want to end up in a "dual-pattern" situation, so I asked CPP if they could design a kit, so they did. What they came up with utilizes 11 11/16-inch Toyota Tacoma rotors (making replacement easy), billet hubs, and CPP's Big Bore metric calipers (along with brackets, bearings, a flex hose, and hardware). Not only does the kit accept the stock six-lug wheels that were originally on the '39, but they also accommodate Wheel Vintiques' new 15-inch six-lug artillery wheels. As for the 15-inch GM artilleries, I didn't have one to test-fit, but considering they're 3 inches wider, it's very possible there will be some interference between the inside of the wheel and the caliper. I did have a solid-style 15 incher handy, but due to 3-inch backspacing, it rubbed on the outermost edge of caliper and top of the caliper bracket. A 3/8-inch wheel spacer seemed to eliminate the problem, but that also reduced the amount of lug threads (borderline being not enough, but there's always the option of installing longer lug studs). Unless you have a wheel with less backspacing, you might be better off going with an aftermarket 15 and avoid any potential "extension" issues.
Even though you can disguise a wheel with a hubcap-which is what I thought I might have to do before CPP came to the rescue-if you have a Mustang II under your truck and want to run six-luggers, now you can.
