OK, it wasn't Crack, but it was a 2-inch vertical crack in the front diff of our '99 Subie Outback. Conveniently located on the passenger side so that gear oil dripped onto the exhaust and created a huge stench.

Then there was the flashing AT OIL TEMP light and a CEL, which translated into a bad torque converter lockup-up solenoid.
Luckily, the amazing Subie mechanic to the Solo stars, Steve Powell,

had come across another '99 at the Ontario Pick-A-Part. A mere 67k on the clock. A couple of hours wrenching on it, and a scant amount of cash compared with any rebuild, and a fine specimen of AT + front diff was mine. Fortunate, because despite the guts of the Outback AT being the same from '98 to beyond the '99, Subaru's choice for the 1999 model doesn't match any year before or since. [Possibly the bad influence of GM's association with the brand.]
When the current trans/diff is yanked out this weekend, I'll try to get pictures of the crack and fluorescent dye, which was visible with the naked eye, no special glasses needed!
Morale of story: Don't by a 1999 Subie with an AT, at least not one with a Legacy platform. :unimpressed: