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; 1933-34 Car, EA
Product Details
Brand: Welder Series
MPN: 563420
Country/Region of Manufacture: Canada
Thickness: 3/16"
Priced individually.