Rear wheel bearings

My bike's an '82 seca with the 4spoke aluminum rims. (xs400rj)
Put 10,000km on then I finally took the gnarly rear bearings out. No luck finding replacements yet... Parts places said 'yeah no prob with the part numbers'...crap... Winter's coming...
For anyone interested in knowing the numbers:
Big one 'under' the sprocket : NTN 6304
it's seal has 'SD 30 52 8 - 1' on it...

The two in the hub are:
NTN 6303 RS on the right
NTN 6203 LU on the left

guessing they're stock at 54,500km...
I'm posting on my cellfone, I hope i didn't miss this info searching and hope this helps someone, and if anyone knows alternate bearing numbers for that 82 rear hub please post 'em?

you just use the international bearing numbers

6303 and 6203 the letters after indicate sealed or not, rubber or steel sealed

I went to a machine shop n got em no problem... Thanks for the info drewpy.
Auto parts stores have what to do with the international numbers... guy kept saying he couldn't find 'his' product numbers... Gotta go straight to bearing suppliers around here...

Anyways I replaced 'em, but still have some high speed vibration... it's mostly smooth until around 70 now, but starts really vibrating over 85km/h...
I'm pretty sure it's the chain or the (horribly scalloped) back tire... seems like the engine vibration is transmitting more through the frame and it's 'shaky' when it's under a load at too low engine RPM's...

Swingarm bushings r toast... Hopefully that'll solve the problem.

I'm wondering if i left it TOO long tho... is there supposed to be play at the connection where a pin joins the monoshock to the top of the swingarm?
Should I make a sleeve or leave it be?

Swingarm bearings are (2): NTN HK2220

Found the problem... I think...
Seems like the bearing behind the front sprocket (layshaft?) is worn out...

Is there any way to replace this without splitting the case?