may i ask why you need seat covers so badly? they look awful. if you MUST have seat covers, poke around some of the mustang-specific supply companies, there are covers out there made especially for mustang seats...the generic ones are gross
hey I have a seat cover in my truck and it has butterfly's....seat is a 60/40 and the 40 is the driver side so the guy that owned it before my put it in (probly his wife) and I left it in there cause it saves the seat ( I work in a shop)
but in the summer when I DD the mustang and the days off my other job when I work at the shop I cover the driver seat with a towell....works and I remove it when I get home.
I almost bought those exact covers, myself. I went with something that looked as close to OEM-style fabric as I could find, instead of some silly prints or whatever that look tacky 9 times outta 10. I also have some groovy faux-leather seat covers that have that biker-jacket-leather look/feel to 'em, but being that they're vinyl, they just make my butt sweat too much in summer and they're too friggin' cold in winter - only good for a couple of months out of the year. Most of 'em run about $15 to $20 apiece (per side) from Autozone or similar places.
They do have some low-back seat covers available at most places (Autozone and Wal-Mart come to mind) where they have a separate slip-on cover for the headrest and a hole in the top of the bottom half for the headrest to poke through. I had a set of those, too, but a tragic accident involving double espresso coffee from QT and a clumsy girlfriend pretty much ruined them (couldn't get the stains out completely) ... but they did fit nice, even over the tops of the GT-style seats I've got in my notch.
I have pics of the whole seat covers somewhere, but all I have handy are the shots with just the front edge of the seats visible (was more focused on dash shots at the time). Gimmie awhile and I'll either dig some up or just snap some fresh shots tomorrow...