Re: Rectifier 1998 Mercury 8 HP
What you're looking for is called "Stator Auxiliary" or the auxiliary stator. It's an add-on to the existing stator. Along with this stator are longer bolts needed to mount it to the existing stator. Which does require you to remove the flywheel to gain access.
Besides that you'll also need the rectifier/regulator that goes with the setup. Rectifier mounting plate, screws, wiring harness, etc etc.
These parts should be avail from the Merc dlr but won't be cheap. I looked up one stator which, at $165, was more expensive than the stator that runs the ignition! The rectifier/regulator runs around $82.
A few good places besides the iBoats Store to look up parts are
www.boats.net www.crowleymarine.com and
www.boatfix.com
Lotsa good diagrams at the following site, you'll need your serial # to get to the correct diagram for your motor:
http://www.mercruiserparts.com/selectSerailRange.asp?doc_nbr=8
Note if you scrounge around, you likely can find the parts a lot cheaper than dlr price (except maybe the stator, don't know if there are any aftermarket ones avail).
eBay is an excellent place to look for parts; for example, any generic Merc rectifier/regulator could be made to work with this setup, and can usually be found for under $50 (or cheaper for used). You can make up your own mounting bracket and external wiring harness if you're handy.
HTH & Happy Parts Hunting........ed