taking my trans apart (a6 si) and ive read that the diff assembly is suspose to slide out....mine doesnt! any advise?

 

Heat the case up, somehow. Aluminum expands and contracts much more quickly than steel, so the bearing/diff is probably just locked in.

Harborfreight has a great cheap heat gun I use, and it's only somewhat likely to burn down your house!

You could also try a hairdryer, but it will probably take longer. A torch is iffy, since you could warp something. The Helms for my Prelude says to not heat the case over 212F, IIRC. (This is easy to verify by flicking some water onto the part you're heating.)

 

They can be a pain in the neck from time to time...did you try tapping it out with a plastic mallet being careful not to damage anything...sometimes they need a tap or two and they knock loose..have someone on the opposite side hold the diff (or you can do it yourself if you are able to) so it doesn't fall out and chip a tooth on the final drive gear.