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.
 Up until now, in order to...  Up until now, in order to run six-lug wheels on a truck with a Mustang II frontend, you either had to shell out some serious coin to have a custom set of brakes made, or perform some questionable modifications. That's all a thing of the past thanks to CPP's new brake kit. |  With the standard-fare 11-inch...  With the standard-fare 11-inch GM rotor, there's more than sufficient wheel clearance-that's due to the rotor's smaller-diameter lug surface. With a 6x5.5 pattern, you need more meat, which means a bigger rotor. |  More meat is just what CPP's...  More meat is just what CPP's kit has with its 11 11/16-inch Tacoma rotors and Big Bore metric calipers-both of which fit nicely in (most) early 16-inch factory wheels. |
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.
 CPP's kit is designed to fit...  CPP's kit is designed to fit the "standard" Mustang II spindle with the perpendicular upper mount (not all MII spindles are the same!)... |  ...Verify this along with...  ...Verify this along with inner wheel size before ordering. |  While the typical cast caliper...  While the typical cast caliper bracket features an integral spacer on the lower mounting hole to indicate right and left, the CPP steel brackets dogleg toward the frame and do not require a spacer. |
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.
 Prior to installing a new...  Prior to installing a new brake kit, if your frontend components look anything but new as my bare metal parts did, now's the time to do something about it. Amazing what a difference a little detailing will do. |  As I mentioned, the rotors...  As I mentioned, the rotors are off-the-shelf Toyota Tacoma items (as are the wheel bearings), but the hubs are all CPP. |  I'm not a proponent of those...  I'm not a proponent of those gadgets that pack wheel bearings with grease-I'd rather spend the money on paper towels and quality grease. However, I do find the Harbor Freight seal driver to be quite handy. |