The notch is on either door on any 986 and 996(at least c2).
I've used 2 Black & Decker trickle charger on both my 01' 986 S & 01' 996 C2 in the garage,both have done their job and cycle on & off as needed.
http://mike.focke.googlepages.com/batteries
No need to pay for the Porsche name on the charger,unless you want to,they both do the same thing.
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-99' Zenith Blue 5-spd...didn't agree with a center divider on the freeway
-01' S Orient Red Metallic 6-spd...money pit...sold to buy a house