https://www.cunninghammachine.com/product/gm-10-bolt-11-inch-drums-20mm-spacer-for-nbs-rear-brake-conversion/
https://www.cunninghammachine.com/product/gm-14-bolt-60mm-spacer-for-nbs-rear-brake-conversion/
Welp, looks like its only for the 14 bolt (doesn't state semi or full float) and the 11"...