Yep! Always re-useable when the machine is decommissioned. I think the total for all of it came to $150. Well worth it for the added stiffness.
The digital level arrived on Monday, so I was able to get the bed to read level@ 0.0degrees all around, then shim the rails to match. They were very close before, but now I'm completely happy.
Today I'm replacing these aluminum bearing brackets with steel. The aluminum here is a real weak point IMO. They just flexed rather than tightening against the rail. This allowed the gantry to be forced off the top of the rails over 1/16"! I'm sure that could have caused some ugly chatter in the Z axis...