left side boom for 430 loader?

[RoyJackson]

really interested in this as well.

do the 200/300 cx series suffer from 'slop' too?

Well, I just got in from a visit to my Deere dealer.
I had a chance to talk to a technician who sets up most of their loaders. He said the loader mount (part attached to the tractor frame) can be shimmed to tighten up the mast, but a better fix is to build up weld on the mount (or the mast, but that requires transporting the loader if you don't weld) and grinding the weld to suit.
The sole adjustment (on the 420 and 430 loaders) is up by the front mount (near the weight bracket), but that doesn't affect the masts.

I'm not sure where Beenthere came up with adjusting at a bolt, but apparently there is no adjustment (other then shimming out) for tightening the masts at that bolt.