I have a 1958 chevy Viking 60. There is a 1957 GMC 370 near me that has the 6 lug wheels and tires. From what I can gather, the GMC 370 is a 2 1/2 ton. My questions is, are the brake drums interchangeable? I know I could swap the whole rear, just wondering about the parts though (mainly getting an extra set of brake drums, not to mention tranny!)