Hey guys & gals, its been a while since I have been on here. I have a quick question for all of you. I am going to look at a 85 GS for sale after work today. The only possible problems he has informed me of is a "driveshaft vibration"

Anyone have any comments on what this may be and how serious and costly it may be to fix?

He promises me a completely rust free car that was previously owned by the daughter of our local mazda dealer.

Thanks for any help!