I haven't actually had this car on the road yet, just finishing stuff up and checking things over. I had the drums off to check the rear brakes and noticed when I turned either axle, I'd heard a clunking noise in the differential housing. I removed the cover and while the fluid level was good and there weren't any shavings in the bottom, I really don't think this sounds very healthy.
I put us a short video on youtube where I have the drum and wheels off and I'm turning one of the axles by hand. I didn't video turning the driveshaft by hand, but it is at least quiet that way:
The car is a 73 Swinger with a Slant and a 904. I'm not really sure what I should be looking for inside of the housing. Are there some bearings that can be easily replaced, or is this one ready for the scrap yard?
