an upgrade to v6r1 still requires program conversion even if you're
already running power 6 hardware.
"Programs have a new format on V6R1. Therefore, programs that were
created for earlier releases must be converted on V6R1 (or a later
release) before they can run. Similarly, programs created on V6R1
or later releases must be converted before they can run on V5R4
or an earlier release."