History of the 4.3

[bobwires]

Hello all

I'm in desperate need of some definitive information about my 4.3. My '97 Blazer has a W engine, and it's shot. rod knocking and it's got 180,000 miles. about 1/8" of slop in several rod bearings...

I need to know what years they had the same engine setup so I can find a donor. I believe I remember seeing somewhere it was '97-02, and '03 things changed.

Is there block numbers to look for, or just any S10's of particular model years?\

many thanks in advance.