I'm about to fit a 6G74 out of a front wheel Drive into a AWD. Is there any differences.

Someone feel free to correct me if I'm wrong, but don't the AWD and FWD have exactly the same engine?!

There is a part of the block that needs to be ground back to clear the transfer case, Can't remember exactly where but someone here will know.

You might want to swap the sump too, the AWD one is different also to clear Transfer case. Have heard of people not having to do this but it may be a difference in transfer case castings. If yours is OK I would fit it just in case. Yes there are a couple of pads that need to be ground of, (angle grinder wityh a cut off blade will do the job). Check against your old engine and you will see which ones they are.

Cheers Dave

have done this a few times, I generally leave the sump alone, you will need to angle the lip on the sump but you can cut the bossess off the block and mod the sump without taking it off