The Service Manual is not an a FAA approved document, it is considered "acceptable" data. There is a difference. A knowlegable IA can explain this in better detail that I can do here. Unless an alternator is an option in either the parts manual (per Serial Number) or indicated in the TC Data Sheet then the swap is considered a modification which requires either an STC or a field approval. I am in Texas and word is out that the FAA is not doing field approvals any more. The only option is to contact a DER (Designated Engineering Representative) and get the approved data from him/her for this to be a legal modification. DER's usually cost quite a few $$$. I don't know if there is an STC for your model, I would contact Kelly for information. I maintain a 57 182 which was recently converted to an alternator with a Kelly STC.