How many hours should I pay for for a replacement of an alternator on a cadillac deville 99. Is it true that they need to take the engine out?

Absolutely not true!!! I would not deal with anyone who tells you that! I my self would be able to change out your alternator in one hour or less. If you have a computer, copy and paste the following link into your address bar and see for yourself how easy it is to acess your alternator: http://www.autozone.com/autozone/catalog/parts/partsShelf.jsp?displayName=Alternator&currentPage=1&categoryDisplayName=Electrical+%26+Lighting&navValue=15700086&itemId=86-0&parentId=57-0

Theomiu, not real sure how many hours you should pay for, it depends on who is doing the job, it is a real pain in the rear, but should not take more than 3-4 hours. As for whoever said you need to take the engine out must not really have a clue what they are doing or are trying to scam you , you absolutely do not need to take the engine out. I hope this helps you :)