Hi

['68OrangeSunshine]

Originally Posted by Kalums

Do I need it? The truck did not currently have one. How would I plumb the vacuum?
New heater core looks identical... Except less leaky, hopefully.

If you don't have Factory A/C you don't need it.

If your old Water Temperature Sensor fits the new engine, use it. If the old set up worked OK then it should work, providing it fits. If it doesn't fit, and you can't find adaptors, you might need the new one.
When I swapped a Mr Goodwrench engine in my '71 Jimmy -- 26 years ago -- the old sender didn't fit the new hole. The new sensor didn't read right. Something about getting some resistors from Radio Shack. Tried that, never worked.
I finally got a manual AutoMeter mechanical Water Gauge.
Now I know exactly how hot my engine is running. Much better detail.