That spring is what pushes the clutch packs together to provide the "posi" function of a Trac-Lock diff.
'03 Mercury Marauder (The Blackbird)
Trilogy Motorsports supercharged #61
Too many mods to list / Driveway Queen
'00 Grand Marquis GS (Silver)
No ABS, no RAS, no Traction Control, manual HVAC,
single exhaust, 2.73 open, and an ugly-ass landau roof.
Exactly what I wanted in a DD: simple.