The stock differentials are "glass." There is nothing that you can really do to check the condition of this. But when you get the car, drain the fluid (look for metal shavings, a couple is fine, excess and your in trouble) and fill it with Royal Purple Synchromax. Next oil change, put in all 6 quarts... Hard right turns own these cars, many spun bearings. Thats all I got right now.
