I found a gauge cluster from a 2001-2004 996 that I may buy. It's got the stainless steel faces. The milage on it is more than my car has but Porsche North Scottsdale told me they can reset the milage to what mine is for a half hour labor.

Will part number 996 641 223 20 70C work in a 1999 C2?

 

No. The clusters from 02-04 are CAN bus while 99-01 are not.