[66gtk]

Have you inspected the rear hub bearings and tightness of axle nut? There was a known issue with the SPF cars, and your chassis falls within the problem range. SPF even issued a warranty and TSB for the repair. I would also inspect your rear suspension shock mounts as they are noted to fail in your chassis range as well. Not intending to pile on, your car may also suffer from rear CV joint failure. All of these issues as they relate to your chassis number range are documented on SCOF's membership site.