According to the
2004 Winnebago Adventurer 35U Parts Catalog there are two possible fog lamps for your coach:
7 138910-01-000 EA LAMP - FOG - CLEAR/ROUND - CHECK TO BE A HELLA 88085W BEFORE ORDERING
7 151421-01-000 EA LAMP - FOG - CLEAR/ROUND - CHECK TO BE A hAMSAR 831458/S BEFORE ORDERING
Also, just btw, if you go the main
Parts Catalog page, select the pale blue 'Serial Parts List' button on the center left, and supply your serial number you will get a complete build parts list for your coach--every part that went into building your particular coach.