CanI replace my 99 Blazer 4.3 with a newer year engine. I am seeing lower mileage engines from 02 and up on Car-part.com, but it does not cross reference that engine. The newer ones have less miles, so I wondered if it was possible without to many changes.

 

No you cant, for your 99 you need a 96-01 motor. in 02 they got rid of the EGR valve and changed the knock sensor with a dif. type.

 

The knock sensor is the biggest hindrance. The removal of the EGR from the mid-02+ engines just means you would need to swap over the intake manifold, but you can use the SCFI spider from the newer engine with your intake.

It has not been confirmed or denied, but I would think that you could rewire the knock sensor to use the newer style mounting.

 

I had04 4.3 motor put into my 98 blazer all they have to do is tap the crank sensor bolt to a bigger size.