You need to get the ranger gasket from Ford PN# F57Z-6584-A take the other one back. The ranger gasket is also reusable so it's the last one you will ever need.
Modern Performance, don't get me started with that moron. You can bend up a 3" system for much less by any decent exhaust shop or take BowDown up on his offer. You can get a 3" downpipe from Sac mustang for about $100
You may want to keep this link it has a lot of the info from the IMON list back from 94-99.
http://www.merkurxr4ti.com/ref/merkur.pdf