presumably they both have backs, so you don't need those.
You want fidelity style film holders -- can be bought new or used, you can find lots used for about $10 each. New can be had at Freestyle http://www.freestylephoto.biz/180903...lder-Twin-Pack
Another option is the Grafmatic film holder -- it holds 6 sheets at once, costs $75 for good used at KEH.
All sheet film holders can be used with any kind of back that your camera has on it, spring or graflok. The crown should have a graflok on it, but no matter, they all use film holders.
I'll give you $5 for your spare body
if you go to www.graflex.org you will find a massive data resource on these amazing and highly useful cameras.