The very issue brought up by Greg is currently unfolding on the "marketplace" forum:
http://forums.pelicanparts.com/porsche-marketplace-discussion/572403-so-72-86-a.html
In short, a very extensive build using an 86 tub and a 72 front clip. Car is registered as a 72 and the seller wants $85K for the car. Apparently done without the DMV being informed, and now it's resell time. How many of you would drop $85K on a car like this?