Thanks all! I understand how things work in manufacturing and know that there can be variances. With that in mind let me ask the questions a little differently. With the info in these books what percentage of the questions in this forum could be answered? I understand that the books are model specific and one book wouldn't answer questions for all models. I am just trying to get a feel for what I would be getting for my money. Their webpage has a few sample pages but they aren't that helpful.