Do you have a test environment? IIRC, BUE 9.1 honors the 8.6 serial numbers. Try downloading 9.1 here:
http://seer.support.veritas.com/docs/264658.htm
For service packs and driver updates, see:
http://www.veritas.com/be_support/www?schDType=ALL&schDVer=9.1&cmd=docPages&product_code=10&pageid=1&sort=&docOp=search&sOrder=null&cat=null&scat=null&can=null&scn=null