I thank it changed with overall length regulations. This was one of the first conventionals in fleets around here.
With a 48 foot trailer and 44,000 Lbs load it was border line. If you positioned the filth wheel to axle the weight with fuel it was over length. When set for proper length ( 60 feet ) it was over weight on the steer.
That was for some state roads and bridge laws are different in others.
Then 53 foot trailers were allowed on Interstate but ticketed when traveling even a a half mile more to a shipper.
Allowable lengths changed over the years and now most everyone wants a conventional.