Remove the small nuts.
With a punch drive the small bolts out.
Support the truck and axle best you can to remove all tension from springs.
Use a slide hammer in the grease fitting holes in the ends of the spring pins to yank them out.
Alternately use a big punch or steel bar and drive the pins out, this can be done from either side, even from inside the frame going out.

Grigg

•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-