roller assy. for 1975 -77 crestline sliding patio door.

I can't take the door off to look or take pictures (cold out).The roller assemblies are mounted on a metal piece that goes the length of the door,the metal piece also is the bottom w/strip.the rollers are about 4 inches from the ends,the ajusting screws are about 4+ inches long The roller wheels are mounted in an aluminum housing Zion ILLinois is on lake michigan and afew miles fromm Wisconsin