Those etype bearings are only manufactured by two companies that I know of, Enduro which are decent quality bearings and JNK which are not very good.
However I’m not sure if the manufacture the 608 2rs etype, the do the 6903 2rs Etype and the 6900 2rs FE type, but only because they have the contract for Treks bearings as far as I know, and Some of the Trek bikes run these bearings.
As for replacing your bearings, if you can get good quality bearings for most of the pivots and then simply run the enduro ones in the other pivots.
I can sort you out with the hard to find bearings and give you a quote on the others so you can shop around.
If you’re interested just message me my email address is kaesae(at)blueyonder(dot)co(dot) uk