As of a month ago or so, I don't believe there were 3:33's available anywhere. Unitrax was due some, but there was a mistake with the manufacture of the gear sets they had ordered. They told me in February it would be at least late spring/early summer before they expected to see the 3:33's.
The choice then became simple for me---I bought a Unitrax 3:45 complete assembly which is sitting, open, on my family room floor waiting for the 3 feet of snow to go.
Steve