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:
Model A Rear Body Mount
Product Details
Brand: Welder Series
Thickness: 3/16"
For model A frames that have a kicked and narrowed rear frame section.
This plate can be welded outside the kicked portion so the body’s rear mount can be used.