Explorer brake lamp/bulb

3157 is the right part, its both rear brake and lights in one.   I got 3156 which is only a brake bulb.
Only two screws need to be taken off on the top (philips)
The 3rd or the top mounted brake light -  not sure what needs to be replied.. will research further.

Battery terminal - use a size 10 wrench.

update: (found this)
http://www.justanswer.com/car/02lk7-1996-ford-explorer-replace-high-mount-brake.html

I'll probably go with the LED hack for <$20 and some weekend work.
http://www.explorerforum.com/forums/showpost.php?p=1950864&postcount=87

options:
http://realbrightleds.com/
http://www.instructables.com/id/Ford-Explorer-3-Brake-Light-Fix/
https://www.superbrightleds.com/moreinfo/top-emitting/high-power-led-flexible-light-strip--nfls-x3/1465/#/tab/Specifications

Item Part Number Description

1 N806539-S101 Nut
2 N621900-S307 Nut
3 N85709-S100 Rivet
4 13A613 Rear Hi-Mount Lamp (Neon)
5 — Low Voltage Wiring Connector
(Part of 13B472)
6 — High Voltage Wiring Connectors
(Part of 13B511)
7 N804405-S307 Nut
8 56911-S307 Screw
9 13B511 Ballast