I logged into {Dishnetwork.com} support chat last night to ask for keys for my three 6.3's remotes so I could UHF remote my three TV1s, and to order a 21.0 learning remote. I ended up buying a 6.4 (plus the free keys for all my other remotes). Cost was $20 + $9 for S/H, and $1.90 for something or other.
Ya know, that was my first thought, but neither the 6.4 or 21.0 remote was listed on the site (at least that I could find). It was late night when I wanted to make a decision, so no way to call Claude. The Tech Chat support CSR was refreshingly helpful.