The spring should be retained in position relative to the axle by the center bolt locating tightly in its hole in the spring perch. The U-bolts should not contact the spring leaves as they will wear and weaken the bolts. The spring leaves are restrained from swiveling by clips normally riveted to a leaf and wrapping around others. Some clips are simply bolted around the leaves. If the U-bolts seat correctly around the axle tube and fit the retainer plates, there is no reason to worry about an additional space caused by using 3" retainer plates on 2.5" mains. In my opinion.
I would not put spacers in to fill the gaps and cause more grief. Your mileage may vary.
Last edited by sweepleader; 01/06/2020 12:34 PM.
