Engine
250 cu in (4.1 L) I6
307 cu in (5.0 L) V8
350 cu in (5.7 L) V8
400 cu in (6.6 L) V8
454 cu in (7.4 L) V8 

Transmission
3-speed manual
4-speed manual
3-speed Turbo-Hydramatic auto. 

Chevrolet El Camino on Wikipedia

MORE SPECS WILL BE HERE SOON