<VV> Manual trans diff. VS. Automatic trans diff.??

[4carbcorvair]

What is the differnce between a differential on a standard trans car
compared to a diff from an automatic car? Can they be interchanged? I
thought I had read somewhere that the auto tranny diff doesn't allow
fluid to be exchanged, therefore would work with a manual tranny. Is
this correct?

Thanks!

-- 
Ron Tinkham

66 Corsa Convertable, 140, 4sp.
Maine