Oil drain hose?
 

Will this fit the oil plug threads on the 496 h.o.

http://www.westmarine.com/webapp/wcs...classNum=50402

Yes, but if you buy the one from Merc for the same money (without the quick disconnect), it has its own swivel and can be tucked away maybe a little nicer..

You will also want to use the dowdy seal with a little bit of #2 or the like.

do you know a part number?

OIL DRAIN KIT
32-865281A02
Includes special tether so oil drain hose can be pulled out through the boat bilge drain hole to drain engine oil. Boat needs to be removed from the water to take advantage
of this feature.
Fits 1996 and newer MCM V-8 engines with metric M12 oil pan drain plug threads.

MCM V-8 (496cid) 12MM oil plug threads. S/N 1A349411 and up, Part number 32-865281A02.

http://www.mercruiserparts.com/Show_...d+Drain+System

No the kit above would not fit because it said this,
This kit is for GM, Chrysler & Most Ford Oil Pans 1/2" -- 20 Thread.
You're thread on the 496 should be 12MM.