When I put the refreshed motor in my car over a year ago, I broke the coolant temperature sender (the one that goes into the passenger side head). Because I have LT4 heads and intake I ordered a 1996 sender. (My car is a 1992).

Since that moment my analog gauge has read 30-40 degrees hotter than the digital readout on the dash. I tried reburping the coolant system a few times but it was consistently higher.

So today I decided to take advantage of the MLK holiday and I changed oil and did a coolant flush - I also bought 2 new sensors (water pump and passenger head),

Voila - the analog gauge now tracks with the digital gauge (or at least the best I can tell given the gauge markings).

It also behaves exactly like it used to before the refresh. So I wont freak out every time the digital gauge shows 200 (because the analog would previously show 240 ish).

The problem was either:

1. Inadequate reburping
2. A bad sender from the factory or..
3. the 1992 sender is calibrated differently from the 1996..

Thought I would share.

Did you reroute the cooling lines at all?

Like the lines that go to the back of the heads?

I would guess if the 92 and 96 have different p/n's then yes, the 92 sensor would have been the correct one to use all along.

Brian- I 'upgraded' the cooling system to a 96 configuration- which was primarily a water pump and different cooling hoses. The basic flow through the radiator and into the heads / block then out again is unchanged. The pipe at the rear of the heads is unchanged too. I'm convinced it was a bad sensor or wrong P/N- I've drained and reburped coolant on this car 10 times in 8 years!

Knock sensors ae also different - stay with the LT1 version.
Basically match the sensors to the computer, not to the LT4.
Bet there is no crank positions sensor on the engine.