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:
For combination 4-link and lower air spring mount on 3" or 3-1/4" axle tubes. Holes for the 4-link are ½” diameter on 5½” centers. The 4-link holes are 2½” ahead of the axle centerline. The airspring plate is the same height as the rear axle centerline. It is designed with a 3/8” center hole for the Firestone F7012, F7076, or F9000 airspring. Note that separate shock mounts are required. (See related products) These brackets can be substituted in our rear 4-link kits for the cost difference. The part number is for 2 brackets.
Only available for large (1-5/8" diameter) bushings. You could use small bushings, but the radius around the bolt holes wouldn't match.
Welded brackets will be set up for 1-3/4" wide bushings.
