Sensors and stuff:

This area got really confusing fast too. Here's the story. You have an oil pressure sender in the same area as the SBC. This is not needed by the ECM in any way to run the engine. Its sole purpose is to run the oil pressure gauge on the dash. There are 3 wires here. One is power, one is ground and the last is signal. I presume this sensor gets 12volts when the key is on and thus triggers the oil light on the dash. Once the truck is running, the pressure increases and the light goes off. OK so that being said the idea is to run the original SBC oil pressure sender in that location after removing the existing sensor. I couldn’t find an answer about just splicing the wires into the sensor in the LSX. Everyone is running their old sender so I decided to do the same. You will need an adapter to make this connection. Remember when I said everything was metric? Most people talk about the ones from S&P performance. They cost double because they are chrome. Auto Meter makes one for half the price so I went that route. There are also 2 other places you can steal oil pressure from. There is a plugged boss in the lower block an some have used the coolant line block off plate that has threads for running a sender. IM just using the one behind the intake because that’s where my factory harness plug is already. Use the other locations if you decide to add a second mechanical gauge.

You have a coolant temp sender on the passenger side of the engine. Don’t take this out unless its malfunctioning. Some have 2 wire units and some have 3 wire. The third wire (the one below the two that are side by side) can be wired directly to your dash gauge. I have heard there are discrepancies between the actual temp and indicated temp. If you only had a 2 wire sensor there, you can change to the 3. The part number is TX111 and the pigtail is S619. (Or use your former TPS plug if it’s a round style) I have a second mechanical water temp sensor. I could have put it anywhere really. Turns out GM was really good with giving us options. If you look on the drivers side in the back of the head, there should be a bung there. Again there is an adapter for metric to SAE on the S&P site, but the Autometer one was cheaper. This is probably a better place to put your dash gauge connection. Some have said it gets in the way of the spark plug wire. But it wasn’t an issue for me. I should note that I had to slightly drill out the adapter to fit the aftermarket probe inside for my added mechanical gauge.

My SBC had oil cooler lines. The new LSX engines don’t need this as much as the old engine so you can bypass it. Most do anyway. My engine used to have lines so I needed to cap off the 2 holes. There are 2 styles of block off plates from GM. One is just flat and is a basic block off. The other has a threaded boss for adding a sensor. It can be drilled and tapped for larger sensors. I believe they come threaded but not drilled all the way through. Should you want to add a sensor, just drill it out. There was a GM part for the cover, but I soon learned there was a separate number for the gasket and then another for the bolts. It was cheaper to buy the kit on ebay.