The 70-81 camaro/firebird/trans am sub-frame is the one I think is too wide for the AD trucks. That is the one I am referring to above. You can make it work but it is not the ideal solution to your need. If you are dead set on a sub-frame then I would suggest the rear steer version from 1st generation camaro/firebirds or Novas of the same vintage.

When I was trying to make the same decision about 5 years ago I talked to several owners who were running the camaro sub-frame and everyone of them recommended against it. It rides great but your problems arise when you try to lower it AND run wide tires. Every with tires as narrow as 205's you can have fender clearance issues UNLESS your rims have enough back-spacing.