It will probably not look anything like the stock strut cartridge, since the stock one (or at least the one that came out of MY supra!) did not have any housing around the cartridge, and a lot of oil came out of the main strut housing. I too have the gr2's, and if its got a round bottom with no plate or anything on it, you've probably got the right one. It just slides into the main housing and bolts back in place.
Replacing the front struts really isn't too hard, but it is a bit messy and somewhat dangerous if you try to compress a spring without the proper tool ( them springs can really fly-don't ask how I know this!)! They rent the tool at most parts stores, so that shouldn't be an issue.
Good luck on the install!