I would not worry about the bearings if you can be shure the rig was well maintained.
So if you own it from new or almost new and maintained it well....don't worry.
Having said that.....
If you buy a used rig with a substantional amount of kms (miles) it might be worth the effort and the money involved to inspect them.
I know of a member of our Landcruiser club who bought a cruiser that showed 280.000 kms on the odo.
Looked like a resonably well maintained rig.
When he asked around about getting the bearings inspected, he was told that there was no need to do so.
However....he got them inspected and guess what...
The bearings were not falling apart but certainly not looking good and replaced. The crankshaft was fine.
You can see pictures of them
here.
So I would recommend that, if you don't know about the history of the engine, and you're in doubt, get them inspected. The amount of money involved in a inspection (and eventually get them replaced) is far less than the money involved in an engine rebuild (if possible at all

)

