Looking at an older sales manual for the 300 series loaders, I found two buckets that have similar numbers to yours. The BW14146 is a standard 61" materials bucket, and the BW14764 is a heavy duty 61" materials bucket; they each have a 9.0 cu ft struck capacity. The 53" buckets have a 6.0 cu ft struck capacity, and the 73" materials buckets have a 10.7 cu ft struck capacity. If your bucket is a high-volume (light materials) bucket, a 73" is 15.0 cu ft, and a 85" is 17.4 cu ft; these would not be common. The Deere configurator shows the two numbers I gave you as the current 61" buckets for the 300CX. Is it possible that either of these are the numnbers on your bucket?