The stock balancer originally on my '94, the balancer off the 1980s fox motor now in my car and the balancer off my '92 F-150 are all the same. Who would have thought?
The fox balancers do fail, but here's my unsolicited take: There is a good bit of extra underhood heat in the SN engine compartment. The elastomer is just rubber (with a decent durometer rating) and heat kills rubber.
One thing I actually wonder: Do you guys have a cheat sheet to know which balancers will rub the water pump (thus requiring radiusing the pump)?