In all fairness, it doesn't have to take $4000 to switch to coilovers. I switched to coilovers on my 66 for pretty much the same price as it would've cost as if I purchased new torsion bars and decent shocks.
Not trying to be argumentative or a dick, but I would be very interested in seeing the numbers on this. Again, not saying it isn't true, just that I would like to understand the details.
