I put a 1990 350 in my 1991 s10 blazer,All the wiring was correct except for swapping a couple of plugs.The only problem is the egr vacuum plug does not have three wires like the one in the s10,Is it ok to use the egr vaccum from the 4.3 liter?

 

Yes, you should be able to use the vacuum solenoid from your old engine. It should perform the same function.