Welcome aboard smithdad.
Rotella will work just fine in the gearbox.I like bel ray gearsaver as I've found I get smoother shifts with it.Many of the tranny oils (Motul,Amsoils etc)are just a 10/40 anyway without the modern day friction modifiers.Some will rec atf but I find this breaks down quickly and my shifting gets notchy.To each his own though.If you like Rotella,go with it.It's as good as anything and you can't argue with the price.
From the teardown condition perspective,I've yet to find anything better than Motul 800 or Amsoil Interceptor-so I use either or of those-whichever is on the shelf at the time.Ipone is good also if you like strawberries-and it's made by Motul.
You'll get lots of advice with the criteria just being whoever presently uses what.I always based mine on what my engine looked like wear wise,top and bottom,when it was time to take it apart.(there's a big difference sometimes,they're not all created equal.)