I bought mine but haven't had time to weld them on. I bought Western Motorsports full length subframe connectors and those things are BEEFY. Like i said, i haven't tried them yet, but i've heard ALOT of good things about them. Of course, basically any name brand full length subframe connectors should fit well and make the unibody alot more rigid.
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Mustang Parts Specialties ripped me off, don't buy from them.
'84 Mustang 5.0 LX
my LX
'89 Mustang GT
my GT