http://www.fuelly.com/car/chevrolet/silverado_1500
Duplicate engines listed.
Probably best to list them with brand identifiers:
http://en.wikipedia.org/wiki/Chevrolet_Silverado
Example:
Vortec 4300 (4.3L) V6
Vortec 4800 (4.8L) V8
Vortec 5300 (5.3L) V8
Vortec 6000 (6.0L) V8
You can figure out the generation or RPO by year most of the time. Users can add notes if they want to says it's an LY5 Iron Block vs. LH6 Aluminum block, etc.
Better to keep it simpler.
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