[Dazzler]

The bearings as you say are standard 8x16x5's, But as I found out, the Diff needs to be the WASP one to allow the use of the 5mm wide bearings. If you try and fit an MMS diff, you'll need 4mm wide bearings. Unfortunately I could only ever find them as open not sealed or shielded.

You could easily modify the diff ring carriers to accommodate the standard bearings of course - if you have a lathe.

Just added some info to complement what we are looking at in this thread, have a read and look back at the sort of engineering effort that was going on to support this great hobby.