I was talking to my dealer about this on Saturday. 2001 was the first full production year although there were some units produced during the 2000 model year.
According to the dealer and I have heard this from others, the early units did have some problems with components and water leakage. I was at Jackson Center in July 2001 where a person was having his 2001 retrofitted with the enhancements that were present in the 2002 produced units.
'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700