um couple things, big thing is there any kind of whining noise coming from the rear, like a constant hum thats with the speed of the car. second excessive play in the rear end. try to move the driveshaft without moving the tires. dont jack it up leave it in gear or park and grab the shaft and twist . go underneath with a rubber hammer and start beating on things lightly. there really isnt much to the ass end of a
stang. see if maybe a brake or fuel line of some sort is loose. check the trunk too for anything. maybe bad bushing in the shackles of the leafs. also a bearing and race ar what the axles inside the rear spin on that are connected to the carrier inside the differential. think of a roller skate or blade if you must.also leave the car in park and have a friend push the car from side to side and up and down. maybe a shock mount is loose or broke or something.try to eliminate everything you can
Anything in the rear right of the car that ... ? 
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