reversing light wiring

i have bought a secondhand engine wiring loom for my mk1 as the old one has a lot of damage and plugs missing. The new loom seems to be missing the plug and wiring that goes to the gearbox for reversing lights. can any one tell me how i can rewire the reversing light switch so it works? The new loom is from a 88 cab gti

Should be part of the MFA gearbox switch ? Read , http://www.vwgolfmk1.org.uk/modules.php?name=Forums&file=viewtopic&t=763&postdays=0&postorder=asc&start=10

Has some pictures as well .