I have just pulled the diff out of my 250hp NB. I thought I had a T2 that had somehow worn out, because of the amount of single wheel spin I was starting to see. Note that the car is only used for sprint events of under a mile, which means 8-10 hard launches over a weekend. In the last 2 years, perhaps 15 events so make that about 150 hard launches. That was apparently enough to wear out whatever was in there. I confess there was probably some wheel hop, to add insult to the injury.

I pulled it out to inspect yesterday, and discovered that it wasn't a T2, but was in fact an OBX helical. I haven't disassembled it yet, but I can slide the internal parts on one side in and out with my finger more than a 1/4 inch. I don't think I'll find much Belleville washer in there.