S5 Vert Diff in a S4 GXL
 

So I have a 1988 GXL and my clutch LSD is not locking up. While I want to rebuild the diff and get it working again, I want to get into drifting with this car as soon as possible. I have the opportunity to buy an open diff from an S5 Vert and weld it to put into my coupe for now until I get the opportunity to rebuild my LSD. Will this work? If not what would I have to do to make it work?

It will, but you will need the stub shafts to go with the s5 diff IIRC