First clean up the Aisin hubs. One can get the O-ring (between the dial and hub cover), hub body to hub cover gaskets and hub body to wheel hub gaskets from Toyota. The Auto hubs didn't use a hub body to wheel hub gasket. You may wish to add one for the Aisin hub.

Be sure to re-install the shims and C-clip that held the axle stub in the auto hub. After you put the shims and C-clip back on, check to see if there is too much or too little play at the axle shaft. One can add or remove shims to get it right.

Take your time getting the allen bolts out from your existing hubs. Put a bit of break-free or some sort of penetrating oil on those bolts a few days before you start working on them. If you don't have an allen head socket, invest in a good one. You don't want to round out one of those bolts.

Do some searching thru the archives. I seem to remember a write up or two about installing Aisin hubs.