i got a 79' blazer, with 12 bolt rear end. i went to replace all u joints in it, and the very rear one is weird. it is not the proper one the parts store's say it should be. its larger on one side than the other. also, there is also /forums/images/graemlins/thumb.gif /forums/images/graemlins/k5.gif /forums/images/graemlins/usaflag.gif casting marking on the inside of the axel that says 85 g.m.. does this mean anything ? could the rear end be swapped from something non-truck ? conversion joint maybe ? this truck is all stock as far as this stuff goes to the best of my knowledge, but the truck has been around /forums/images/graemlins/rolleyes.gif /forums/images/graemlins/whistling.gif /forums/images/graemlins/1zhelp.gif /forums/images/graemlins/tongue.gif /forums/images/graemlins/ignore.gif(many owners). thanks for any info in advance.