If you are trying to identify which part you need try www.mercruiserparts.com. Based in California, so not handy, but web site has full schematics, parts i.d. part numbers, and engine/leg model i.d. plus actual serial numbers. Most mercury/mercruiser dealers are pretty swiched on and can obtain virtually any part, sharpish.Pal of mine needed the support bracket/mounting for his leg hydraulics cos it was rotten due to a deck leak above it. Not exactly a high volume part, and a part number which has been superceeded umpteen times. Ordered on a Monday he had it following Friday....
Hope this helps,
Pete