Shatz might take some interest in this since there was a discussion a week ago (maybe more) about exactly this topic.

97-98 S and V90 and 960: locking differential optional with cold weather package

96 locking diff standard all RWD 900
95 locking diff standard all RWD 900
94 locking diff standard all RWD 900
93 locking diff standard all RWD 900
92 locking diff standard all RWD 700/900

The "Cold Weather" or "Nordic" package that included the locking differential apparently applied only to 97-98 960 and S(v)90 cars. Other than that the package included temp gauge, heated seats, and mirrors. That particular package did not exist across the range of 92-98 however, varying among years. It appears as if the heated seats and heated mirrors were not always included with a cold weather package. Heated seats (example) were standard in 92 but available as part of the package later on.

Confused yet? It's really pretty easy. Volvo dropped some standard features along the way, but bundled them together later on.


--
1992 940 wagon, very low miles
as well as others.