I need to replace the engine in my 95 blazer, VIN 'W' - CPI. Can I use any year block with my top end or would I have to replace the entire engine if I went with one from a newer vehicle. If I went with a newer engine for example - can I swap in a complete 99 motor with my ECM or do I need the ECM off the 99 as well?

 

'95 is OBD1 pcm and the batch fired CPI. A '99 pcm wouldn't work with the rest of your system (4L60 instead of 4L60-E IIRC). The heads would benefit you, but I do not know if there are any other differences that would prohibit the swap. I also do not know if a '99 long block (minues the intake) would work. I'm fairly sure that it would bolt up to the truck, but don't know if your CPI intake would bolt up.

I don't know where you live, but if it's someplace warm, you could always travel around to several junk yards and swap parts just to see what interchanges. Look at the intake port spacing/shape between your motor and the later vortec. Look for other design differences on the outside (location of sensors, etc.). I will tell you that the oil pan on the newer 4.3L will be different (aluminum vs. stamped steel), but there again, I don't know if they interchange and they very well could.

 

When calling around for a new motor, I have been asked the question if my spark plugs are side mounted or top mounted. I have a general idea, but are the top mounted plugs mouted through the valve covers or where?