I have a 2002 chevy blazer with a bad motor.I can get a 2000 model 4.3 but I don't know if it will work in my 2002.I was told a 2001 will work if I swap the intake.

 

2000 to 2002 should be compatible to my knowledge. There should be no reason to swap the intake as they are identical so don't take advice from the person that told you that!

 

I forget when the knock sensor and EGR change over was, but they are fairly easy to spot the differences if they are indeed different. IIRC, it was sometime in mid-02.

The knock sensor on the later engine is held on by a fairly small metric bolt and has two wires while the earlier engines used a single wire knock sensor with a tapered thread boss on the underside that threaded directly into the block. If you have the later design (two wire sensor with metric bolt), then you will want to have an adapter made to bolt your original sensor to an earlier (96 thru mid-02 IIRC) block.

The EGR valve will either be there on your current engine or not (front/center of the LIM). If not, then swapping the LIM on up from your engine to the donor should allow you to go as far back as '96.

I believe that those are the only two changes that could give you headaches if not properly accounted for before dropping the replacement engine in.

 

I would recommend doing the intake gaskets anyway while the engine is out. It is much easier to do then as opposed to with the engine in the vehicle.

 

What he said about the manifolds and intake!!! Note this would include switching the exhaust manifolds too. However, my 2001 does have the later knock sensor and also I know that replacement engines are listed with between 2000 and 2001 being the breakpoint for the knock sensor types, so I think the knock sensor will definitely be an issue for the OP.

 

Yeah I'm dumb I was only thinking upper intake manifold not the lower my bad