RFC1213 defines sysUpTime as a 32-bit counter in 1/100 second.  From the RFC's definition of sysUpTime:  "The time (in hundredths of a second) since the network management portion of the system was last re-initialized."

All PacketWise images and models will have the same behavior after the sysUpTime value reaches 497 days, the sysUpTime polled value resets to zero (0).

SysUpTime MIB supports 32-bit = 2 to the 32nd power = 2^32 = 4294967296 (Timeticks)
Converting time ticks to days = ((((4294967296 /60 seconds )/60 minutes )/24 hours )/100 ticks per second) = 497.1 days.