Need a handling guru to find my problem. Background: built a frame for my '39 out of 3/16" wall 2" X 4" on a frame jig. all is square with the world. MII style front suspension with Detroit Eaton springs, tubular A arms and properly aligned. Rear is Ford 8.8 with air bags (50 PSI), triangle 4 bars and 7/8" sway bar. No sway bar on front. All goes well until about 60 MPH then the slightest outside force such as crosswind or center crown will upset the vehicle stability. The last test (above 60) resulted in a rocking motion that frankly scared the hell out of me. This car should be stable at and above this speed but I can "feel" something is wrong. Everything is new except the tires which have proper pressure. Anybody have an input? Going to disconnect the sway bar and see what happens tomorrow.