[blucar]

From my point of view, the difference between a solid I-beam front axle and modern IFS Mustang II units boils down to how much safety do you want in your ride.
I would never consider taking the original style of 'buggy' springs and 2" dropped axle out of my '36 Ford.
My '36 has a highly modified engine, late trans and some upgrades to the suspension. When I was younger I thought nothing of driving the car like a mad man, many times in excess of 100 mph... I spun it out a few times, once to the point that the car did a 180 and I was driving the car looking out the rear window while trying to steer the car off of the road... I was 20 years old and still almost wet my pants over that one..
I currently have two other cars, Resto-Mods, a '39 and a '49 that have IFS M-II type front ends w/disk brakes, etc.. Both of these cars are driven on the highway/freeway at prevailing speeds.. I have encountered many situations where some idiot has done something stupid which has caused the traffic to suddenly stop or divert... My modern suspension/brakes saved my butt... I stopped in a straight line and/or altered my course without loosing control.. I know my '36 Ford would have went into an uncontrolled skid which would not have resulted in a pretty picture.
Two of my friends have wrecked there early Ford hot rods because they could not stop in a safe manner when the freeway traffic stopped.
If a person wants to drive in the right lane a 50 mph, then the solid axles are fine.