Tranny flushing

[Dave_Vrba@mail.sel.sony.com (Dave Vrba)]

     Listers,
     
     Finally getting around to draining the Valvoline 80w90 gear oil from 
     my '62 MKII tranny.  (It's been on jack stands since early fall fixing 
     the "while your at it" list)  It was decided that this stuff would 
     attack the "yellow metal" we have in our trannies.  I will put in 
     plain ole engine oil, probably 20w50 or the like.
     
     My question to the list.  What can I use to flush out the tranny 
     before filling with engine oil?  
     
     TIA,
     
     Dave
     '62 MKII Sprite
     Dublin, CA