There are very few options on this, especially for the 65RFE. Used cores are hard to come by, so you usually have to send yours in to be modified. New from the Dealership, these run about $650-$700, so you are better off searching for a used core to ship off, or hopefully you can afford a couple week downtime while yours gets modified.
Super Street Performance and Sharadon performance are really your only good options that I'm aware of. L&M customs can do this for you as well, but many customers have said that Mike has been tough to get in touch with as of late...Good product, but he probably just has more work than he can handle at the moment.