I believe your information will be inside this link somewhere, But to be 100% right we will need your engine serial number.
If you know your engine serial number just hover your mouse arrow cursor over your engine size and find the engine serial number that is within your serial number range.
This link is Bam Marine of florida inc, a big Merc dealer that does things right to help you find what you need, Also their web site is easy to use, At least for me because it looks kind of like what a normal mercruiser dealer would use when looking up parts. http://www.mercruiserparts.com/selectModels3.asp?type_id=MERC
try alian's sales and service in cocagne new bruinswick, they have the largest supply of used parts on the east coast. www.allainsales.com or phone them at 506-576-6621, you will need your year make and serial number when you call and i never had any problems with shipping.