I like the ruffstuff perches, one of the few places with narrow ons that are also long, not for a trailer axle.
The ones I needed were to fit about a 3-5/8” tube, they wouldn’t custom make them at the time so I ordered some for smaller tube and machined the radius to suit.

Wouldn’t weld a gap, get them to fit real tight before welding in place.

Also, don’t forget to carefully measure and set pinion angle before welding spring perches on.
Tech Tip with excellent resources linked here.
https://www.stovebolt.com/techtips/driveline/setup/index.html

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-