ok I replaced my drivers side outpit shaft seal and filld it up with gear oil. I drove it around the block and it started to smoke from under the engine"gear oil hinting exhaust" and i could not figure out ware the leak was coming from so i cleaned it up and checked my seal and then drove around for another ten min. Then all of a sudden my center diff was shot( had been clunking for a little while and had plans to replace it).
I got it back to my shop and looked down and it looked like there was a bolt missing from the front of the case and that seamed to be ware the gear oil was coming from.So i threaded a bolt in it and im not sure if there was a spring and ball or if it was just a bolt or what. Here is pics of ware im talking about.
(the rusty bolt is what i threaded in to ware the fluid was leaking out off)

So what was in here that backed out??