A fair amount.
The AD springs taper in at the front just like the frame does.
I seem to remember the spring center bolts being around 26" center to center, but pull a tape measure to be sure.
My guess is that the GMC 7500 is around 34" center to center, but I don't have one to measure.

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-