Same thing happened to me when I used the weld washers at 100 foot pounds. I had a spare set of washers (may have been Centerlines) that are all steel. I think the welds may me some form of cast washer. I'm glad I noticed the failure before making a pass on the bad washers. The weld washers actually broke into a few pieces when I removed them.
92 Notchback best 1/4 10.52 @129 w/ a 1.42 60. Dart 347, Novi 2K, NOS wet kit, Victor intake, Victor Jr stage III heads, Jesel shafts, Liberty shifted TKO, Currie 9" w/ spooled 31 splines. 99 GT Saleen clone w/ 351 body kit, Vortech SQ, VT 302 w/ stage 2 heads.