Are you sure you have a 3/4 ton rear end???
I was under the impression that the brakes on the
'48-'51 3600 used the spoon adjuster to turn the star
wheel. The pinion stud adjuster was on the wonton and
other heavy's.
Someone may have swapped out the HO52 for an HO72 rear
axle at some point.
http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0513.htmDG