[Macroni]

I would say that type of "rule of thumb" varies by vintage. Hit me w/ the obvious stick. The 996 & 997 cars due to availability are easier to measure in a linear methodology, supply and demand. The older cars 83 through 98 have many more variables that needed to be weighted in the purchase price. I would venture that you could make a very smart purchase of an 83 through 89 Cab. I have noticed them popping up here w/ low miles at very reasonable prices. When you calculate the lower mileage they are trading for a lower overall price.