I'd never heard of it either, but I did a search on Google, and it does exist. I didn't look closely at the results, but ut looked like all of them were on muscle cars. Type "3.42:1 chevy differential" in at
www.google.com to see the results I got.
If it were my truck, I'd spend the money I would spend to regear on getting more horsepower out of the engine.
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'04 Cavalier coupe M/T 2.2 Ecotec
Supercharged 14 PSI boost, charge air cooler, 42# injectors
Tuned with HP Tuners
'86 3/4 ton Silverado
350 V8, 4x4, 4" lift, 1 ton axles swapped, converted to 4 wheel disc
35" BFG Mud Terrain T/As
Shortened to 109.5" wheelbase for those tight trails
http://www.boycottpepsico.com/default.aspx
You see "Fresh oil, loose gravel"; I see "Free undercoating"