I just replaced the one on my 1994 Johnson and all I had to do was knock out the pin holding up the hydrualic's swing them out to get to the back bolts. I'm sure your Yamaha is different. My V was sold when I did the job so I went with the cheapest motor I could find but it seemed very solid and was not made out of metal. Here's a link to the one a purchased and a quick serch you should find one that fits your motor.
http://cgi.ebay.com/ebaymotors/New-T...QQcmdZViewItem