Belltech 3100 is a 1/2-ton spindle.
(with 1-1/4" rotors)
These will work.
http://www.summitracing.com/parts/WS...AN&prefilter=1
Summits website is screwed up when you enter 1987 as the year.
You want a 73-87 C20 spindle.
Performance Online sells them also.