what is the curb weight of a 1973 F-250

With a regular cab and standard 8-foot bed, you're looking at right around 4700 lbs. including all fluids, lubricants, and a tank of gas.

Keep in mind, if you tow with a flatbed trailer you need a minimum of a 148” deck length (for a standard cab 8’ bed 133” wheel base truck). If renting a trailer, the newer U-Haul trailers work fine if you don’t have oversized wheels/tires, but the Penske trailers are only 144” deck, so they won’t work.

Mines 6100lb dry

My 73 is 6000lbs