My car is an 87 milano gold 5 speed, and 2 times recently when i start the car there is a scraping sound from there rear of the car for about 5-10 seconds then it goes away and seems fine after that. It only does it in neutral right after I start it, no other time. I checked the oil in the transmission and it is fine, any other ideas of what could cause that? All of the flex joints and other driveahsft parts were replaced shortly before i got the car.