I think a member had some info about tonnage being the approximate load capacity of the steering axle. I'm gonna' look at the GM Heritage pages for mine and take a guess at empty front axle weight, I'll report back.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy