The crossmember is where the front arms mount. Custom brackets are required for the rear arms. Sounds like you are only getting the long arms for $500. Not a bad deal, they run over $200 a piece. Sometines the spares can be found. Make sure you are getting the full lower and smaller upper (it attaches to the lower arm). The stickler may be the frame mount for the rear arms. I do not think I have seen them offered anywhere.
I have a 4.5" long arm on the missus' 09.
NOTE: The install is not for the faint of heart. It took me 4 days to install the lift. You can get the directions on line, maybe at Quadratech.
His 14 Anvil JKUR-X
Hers 09 Blue JK
Kid's '08 Yellow JKU
'13 Black 10A Rubicon JKU