I have always found that the factory service manual is better. I use to buy the aftermarket ones in an attempt to save some bucks but ended up getting the the FSM in the end. The problem that I've mostly encountered w/ aftermarket manuals is that they try to cover a range of years. We all know that things will change slightly even in the same generation.

So back to the original question... The dealer may be able to help but that would be an expensive route. Try eBay. I've bought various different ones that are on CD out of curiosity. All were bootlegs. Some are aftermarket, some are factory with non-US models.