Hello all, I'm new to this site. I just picked up a super nice high performance 1978 Mustang Coupe 5 spd. This is my 3rd Mustang II. Previously owned a '77 Cobra II and a '78 King Cobra. I just love these cars. The Coupe is running a '71 302 balanced and blueprinted, 5 spd. Tremac and Auburn 3:55 rear. The guy I bought it from put all kinds of HP goodies into her. I just started getting a driveline vibration I'm having checked out tomorrow. I removed the rear spoiler and ordered a new front spoiler. I'm getting the Magnum 400 wheels I just can't decide 215 60 15 or 235 60 14.