Relative to 496 Mag
1. What are the specifics regarding the Temperature SENSOR (#7) 805218T versus the Temperature SENDER (#8) 806490T?

2. Electrically, where does each connect, and what is the difference in information they provide?

Going off top of my head the top sensor provides info to PCM and bottom sender for a gauge. Both are in the closed coolant crossover on 496.

Thanks Ryan00TJ.
I believe you are correct since the SENDER is nearest the thermostat and it makes sense to gauge the water temperature at that juncture. I'll check for continuity from that point to the dash gauge to be certain.

You want the tan wire going to crossover sender. This is correct sender for your dash gauge water temp. The sensor on other side of crossover is ECT for the PCM555.

ECT......