Alternator

as long as it will plug in correctly although it may be different amperage.

Hi Becky,

Here is the part number for the 2002

http://www.amazon.com/ACDelco-334-1449A-Professional-Alternator-Remanufactured/dp/B0031I9R9S?ie=UTF8&keywords=ACDelco%20334-1449A%20Professional%20Alternator%2C%20Re-manufactured&qid=1465266531&ref_=sr_1_fkmr0_1&sr=8-1-fkmr0

here is the part number for the 2006

http://www.amazon.com/ACDelco-25766345-Original-Equipment-Alternator/dp/B000IZ0U98?ie=UTF8&keywords=2006%20Cadillac%20CTS%20v6%20alternator&qid=1465266472&ref_=sr_1_fkmr1_2&sr=8-2-fkmr1

They look kind of close but I don't think it will fit, sorry

Let us know how it goes

Best, Ken