Pure speculation but it's possible the newer part number has higher capacity contacts inside. They may have found that the switch was somewhat over rated so they increased the size of the internal contacts in the later version.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250