WheelAdapter.com is your number one source for wheel adapters, wheel spacers, used wheels, and wheel studs.
Fred Goeske is the owner and knows his stuff. If you want to get a good laugh, ask him what he thinks of alluminum adaptors. I was in tears with his reply. He wanted to know if my wife was good looking so he could hook up with her after I killed myself using alluminum adaptors. Coming from an old dude just cracked me up.
I spent about $700 shipped for my adaptors which were solid steel (heavy sob's) Mine are 2" thick to get the correct offset. Not sure what offset you would need.
The new wheels are hub centric (the hub centers the wheel instead of the lug nuts).
You can get aluminum ones on ebay for half the cost. Could be risky with the weight and torque?
Good luck, new OEM wheels on older trucks are macho.