Long or Short Shaft?

[jumpjg]

How can I tell if my 1978 Merc 402 is a long or short shaft motor? Are the dimensions standardized across all outboards, or is a Merc long shaft different than other mfg's?

Thanks for the help,

Joe in St Louis

[boats.net]

They are standard across the board, short shaft 15", long 20", x-long 25" and ultra-long 30".