When we ran a full service chassis fab/turn-key hot rod shop a number of years ago, it was always useful to have threaded things around to weld into the frame for some kind of mount, etc.
Here’s a list of all our threaded things for your reference:
Mustang II Boxing Plate; 1953-56 F100, EA
Product Details
Brand: Welder Series
MPN: 665320
Country/Region of Manufacture: Canada
Thickness: 3/16"
Priced individually. Will not work on 57 Ford pickups.
According to ELpolacko on the HAMB:
53-56 = 4" tall frame @ axle centerline
57-60 = 5" tall frame @ axle centerline
61-64 = 5.5" tall frame @ axle centerline