the vortec swap is not very hard at all. The vortec 350 is the easiest, but the motor is real hard to find. I pulled mine out of a 99 Suburban that was wrecked in the back side (I have the inside on finding hard-to-find 4x4 stuff).
When buying a motor like this, make sure you get the whole engine wiring harness and computer. If you cannot get the ecm and harness, try Ebay, but you will be paying a little more seperate from engine. When I pulled the old motor, I went ahead and changed the transmission pump seal ($1.99 at transmission shop, looks like a axle seal on a 10 bolt) and put a new torque converter in (just a slide in slide out deal). If you have an 86 like me or newer, you will have alot of wires to deal with that you will not be using on the new motor. I just put them in wire looms and dressed the engine compartment up while I can get in there (its not every day that you can stand where the engine was and deal with all the wire monstrocity that GM blessed these vehicles with). The new vortec harness was reworked by a friend of mine that does it for a living. He takes the harness and pulls everything you dont need out of it, plugs it up to the motor and ecm and all you have to hook up is five wires (yes only five wires).The only original wires that you will be utilizing is your gauge wires(volt,oil,temp,ect).
When you set your new vortec in the vehicle, the motor mounts will be the same (thats why its best to have a vortec 350 instead of a vortec gen 3 engine which requires alot more work). When you hook up the wires from the new engine (on my setup) there is one wire for ignition, for B+, tach, starter, and fuel pump. By the way, you will have to run a 60psi fuel pump. I got mine from Autozone (its a inline, framerail mount).
If you have at least a 2 row radiator from your old setup, you can still use it.
I hope this helps you out on how this works. If you have any questions, Ill be happy to answer them. After I get my front clip back on, Ill post pictures of the finished blazer.
