d.fens
+1y
The Thorbecke kit looks to be Mustang II based, similar to what Fatman Fabrication and Chassis Engineering have been making for a while. Works okay on half-tons but doesn't look stout enough for a 1-ton. The Mustang rack isn't the hot setup for really heavy cars / trucks.
Porterbuilt (Porterbilt?) have a crossmember and control arms for C-10's that, from what they told me on the phone, they can modify for duallies.