That makes sense then. The Classic II buckets with the speed holes were later in the production of CIIs, so your bucket would be from the beginning of the CII period/end of the Classic era.

Schools were buying Classics right up until Apple said "we literally don't have any more." If they had more logic boards than buckets there at the end of production it would make way more sense to order some little plastic plugs than to order a whole new run of Classic buckets.