What's the difference between two wheeled four-wheel cab pickup truck?

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I have purchased a 1972 GMC pickup four-wheel-drive, minus the engine with a six-inch lift kit. But the vin number on a cab is TCS 232. I think this is a 2 Wheel Drive cab? Since I am new to this classic truck .I'm 56 years old I need to lower the truck to a reasonable height so I can get in.maybe stock-or 2 inches more . When I lower the truck will there be a problem with the transfer case.hitting the tunnel.It has a 203 transfer case with a 350 turbo transmission.one more question, please is the 203 transfer case standard on the 1972 GMC or is it the 205 case. Thanks guys.