From 1987-1990 the StingRay 5 used AlNiCo magnets in a the straight across "Soapbar" covers.
From 1991-2008 the regular production StingRay 5 used ceramic magnets in the same soapbar covers.
From 2006-2008 the regular production StingRay 5 used ceramic magnets in a flanged straight across cover. From 2008 on these would be AlNiCo magnets.
At this time the pickups changed from a physical "phantom" coil on the pickup to a simulated phantom coil circuit in the preamp.
The dog ear pickup covers were introduced on the StingRay Special 5, which uses Neodymium pickups in 2017.
There are limited editions that will have various configurations that differ from these conventions, but this is a general guideline for the regular production 5 string StingRays.