i decided to switch my fluids over to sythetic... i'm going with either the amsoil (if i can get it locally) or the mobil1... now i was wondering if i have to do the "total oil change" or if i can just do a standard oil change? also is there anything special i need to know about changing the fluids in the gearcase & primary?

 

You'd be alright with a standard oil change. Nothing special, just do it "by the book".

 

If you're worried about the little bit of dino remaining in the engine mixing with the synthetic, don't- they're 100% compatible. (This can be verified at any oil manufacturer's website.)

As for the idea of doing a "total drain & purge" of the old oil, I wouldn't worry about that either. Some folks do it, and that (along with adequate maintenance) will probably get them 150k miles out of their engine.
Others just do a "regular" oil change, and that (along with adequate maintenance) will probably get them 150k miles out of their engine as well.
Just depends on how complicated you want to make it...