I don't have the procedure as i will be done by local DellEMC team. We will upgrade DD9500 to the same code level as DD9900.  DD9500 will be shutdown, removed from rack and replaced with DD9900 head.  At this point head-swap process is initiated and then we wait. How long?  Depends on the size of your current configuration.  
Hi Team, Greetings! One of our customer is looking to upgrade the capacity on a DD9500 asset. However, new & upgrade ordering are EOL for DD9500 from August 15th 2020.Hence we thought about head-swap. Is it possible to perform head-swap on DD9500 with latest DD models and use the existing ES30 & DS60 shelves? Thanks! Best Regards, Ravi Shastry  
DD9500 Head-Swap