See if you have a "Q" (.332 dia.) drill bit. I have a tap for a 1/8" NPT, so it won't cost you anything. I'm sure I can come up with a plug also.

  I LOVE IT!  Now if it will only stop the clutches from chattering we'll be in good shape.  How bout heatin it up and addin cream -n- sugar? Could make a nice fall foliage beverage to go with the cool brisk nite at the track.  We could even whip it up with the tap that DaveM is supplying.

I don't want to be pessimistic, but you might have a cracked or broken posi clutch spring.

O.K. I found all the needed "TOOLS" to do the Drill,Tap,Drain deal, Now where do I drill the hole? WHOOPS, I know, close to the bottom, but how do I miss the internals and not leave part of the bit in there? THANKS  Mark  

|UPDATED|9/16/2011 5:22:31 AM (AZT)|/UPDATED|

If you buy gear lube from GM they will tell you it already has the posi additive in it....put the other separate bottle in anyway....don't fall for that "One size fits all" crap.

Yup..ya needs to drill the hole in the bottom of the diff....I saw somewhere someone had a pic, and a template for doing this. Don't know if it was Mid Am, or who....

 The process worked VERY WELL. All is quiet and smooth. Teflon tape on the plug, and not a drop of a leak on the floor.  On to the next project.  THANKS to all who contributed.

There is a flat boss on the bottom, just behind the yoke. I drilled about 3 inches rear of the seal. Do not go to deep as the pinion is close in there. Once the oil starts to seep I stopped. Be careful to clean out remaining depth. You can put a piece of copper tubing or rubber hose on the drill bit to limit your depth, and not contact the pinion. Once you get the tap started and a few threads made, you can continue with a flat tap on bottom, less the starting tapper. The tap will contact the pinion before all the threads are cut, thus the need for a flat bottom tap.  Hope this makes sense and you can figure it out.  Mark