[blucar]

I have a friend that has two hoists, a two post and a four post.. When doing suspension work, i.e. front or rear of a vehicle, he has found out the hard way the a vehicle on a twin post is very unstable.
Once a vehicle is on the arms of a twin post and has been raised off of the floor, my friend very carefully checks the position of the frame mounts before the vehicle is raised very high. Once the vehicle is completely in the air my friend attaches safety straps around the frame and lift arms..
My friend learned the hard way to use safety straps on old cars.. He was working on the removal of the rear end from a '34 Ford coupe. The car had an OHV V8 and a late model rear end. When the weight of the rear end was removed from the car, the counter weight of the V8 engine made the car fall from the hoist arms..
Of course the placement of the lift arms probably contributed to the "unbalance"..
People that work on old cars, especially those from the 1930's should keep in mind that the old cars were not designed to be lifted by their frames. The old cars were generally lifted via the axles with axle stands placed under the axles..
The old "in floor" hydraulic lifts had movable cross brackets that could be positioned on the I-beam rails to securely engage the front and rear axles of vehicles..
A common use for the discarded EFV8 axle housings was to cut the hub end off, cutting a "U" notch into the end that would fit very nicely under an axle. The large flare of the banjo end sat squarely on the floor..
Through the years I have picked up a couple of sets of early Ford axle housings at garage sales/swap meets, that have been modified into axle stands.