The reason they rub, is because the 93 Cobra has rear disc brakes and the axles are wider. So the GT wheel requires a little less backspacing.
Don't use washers!! You can get wheel spacers which are made of aluminum. You can get them to match you lug pattern. Their available in 1/8" all the way up to 1/2" thick spacing. Their available in Jegs catalog. I had to use a 3/16" set on the front of a 95Gt I had. I was using 5" wide Weld Draglites. They came with the wheels though. This was before they came out with the XP series designed for the 94up Mustangs. I never had any problems though. You probably wouldn't want to use more than a quarter of an inch spacer on the back though. Anymore, could put too much stress on the studs. You might be better off getting different wheels.
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Ron Meyer
67 Mustang coupe (289,Windsor jr heads,4spd,3.55 posi rear)
86 Mustang SVO (Turbo 4cyl., 5spd)
79 F150 4x4 (Soon To Be FE Powered)
<font size=-1>[ This Message was edited by: RonMeyer on 1/25/02 4:27am ]</font>