I'm having these items replaced now and posting them to add to the collective database of E500 ownership repair experience:

>A/C Evaporator
condition: system was still blowing briskly cold, but required a tad bit of R134a to be topped up annually, diagnosed slight leak at evaporator

>Upper Engine Wiring Harness
condition: no outward performance or drivability issues or symptoms (@ 42.9k miles)- - however this part is being replaced now as the old part is certain to premature failure

>Complete Rear Window Sunshade Hardware: motor/arms/shade
condition: upon full retraction the shade did not seat completely level into the rear hat shelf; it appeared that the side behind the driver seated rested slightly higher vs. the opposite side

-fad
'94 E500 (42.9k)
...etc.