Axle and trailer mfg do not offer or make a suspension lift block set up for a multiaxle leaf spring suspension. Dexter doesn't recommend using them on their axles.
Lift blocks on a commercial trailer will not pass a required annual vehicle safety inspection.
Lift blocks add even more side stress to the U bolts/top plates/spring keepers/spring hangers while side scrubbing around corners or backing maneuvers which is one big reason their not recommended.
Single axle trailers have no side scrub events so many folks use them to gain frame height.
