I HAVE A 94 S-10 SS WITH A BLOWN MOTOR. THIS IS THE SECOND BAD MOTOR AND I AM LOOKING TO REPLACE IT. I WAS TOLD BY SOMEONE THAT A 99 WOULD WORK AND THEN THE GUY I WAS GOING TO BUY IT OFF OF SAID IT WOULD NOT WORK. CAN ANYBODY CLEAR THIS UP FOR ME. IT HAS THE 4.3 IN IT.

 

The 99 will not work without major modification. The block is initially the same, but the heads and the intake are drastically different. You'll need the engine from a 94or older as long asit has the OBD1.