Finally thinking about rebuilding, trans question

[jlspec]

Ok, so I'm finally thinking about rebuilding the trans. Currently my second and third will grind a little when I shift fast, so I'm guessing I'm in need of new synchros. Now when rebuilding would I need to ask the shop to use the synchros from a 92-93 trans or is Toyota automaticity selling the new dual synchros in place of the 90-91 single synchros?