OT! tune port chevy I.D. ?'s

how do you tell the LT1, LT4, ect apart? the engine i'm questioning has elec' water pump. alum heads, distributorless ignition and this # on the pass side behind the head. 10125327. supposed to have came from a 01 firebird which would be an LS1....right?... this still has the "old style" exhaust manifolds with the center two ports side by side.
thanks-rp

 

An LT1 and LT4 look the same on the outside except the intake is red on the LT4. The LT1 has a square looking intake that is low and only a few inches above the valve covers. Both the distributor and water pump run off the front of the engine and no belt is needed for the pump. An LS1 is all aluminum and has a water pump run by belt. The intake on an LS1 have the runners showing at the top of the engine. The LS1 is distributor-less with coil packes (one for each plug) mounted on the top of the valve covers. LT1 was from '93 to 97 and LS1 from then on. As a side note the LT1 had a little brother (265ci.). Casting on the back of the block where the transmission bolts up gives it away.