American GPS is a 10 bit base time calendar. The start time was set in the 1980's. The time base ends 6 April 2019. Some GPS units require a firmware update to reset the time calendar, if not, positions will be incorrect. Does the 550 Mustang GPS require a firmware reset? Several of my hand held GPS units have been updated...the manufacturers contacted me and warned that
without time firmware update, positioning errors would probably occur.

 

First I have read or heard of this. I guess we'll soon find out what 'might' happen

 

Thanks for the tip tsunami. I just hooked up my Garmin, and sure enough there was the update. Without your tip I would have been taken up that certain creek without a paddle the next time I used the thing.