i have 68'b body with 440, non ralley dash, i am wanting to keep the factory temp gauge working in the cluster and i am putting aftermarket temp guage under the dash, my question is, i do not have 2 outlets on my water pump for another sensor i wld have to take off the pump and drill another sensor hole, i want to hook the factory gauge and the new temp gauge on the same sensor, i have not been able to crank the car to test it yet, putting new dist. in, i was wondering if anybody is doing this? will it work?

Isn't there a hole for a sensor behind the alternator bracket? It might be tough to see.
There's usually one there as well as on top.

not on this set up, i have pieced together a 73motor home 440 and i an early water pump housing, earlier 60's i think, there is only 1 sensor hole on this water pump, i have all but taken the water pump off, , i was hoping that the 1 sensor wld run both the factory guage and the new aftermarket guage, the aftermarket guage does have the same sensor, however i do not know what is going to happen when you run 2 gauges off the same sensor?

Just for the record so everyone who sees this knows, you can't run two electrical temp gauges off one sender. Will not give accurate readings.

i had not thought about the block idea, i think i have come up with a solution, i am going to run a tee on the heater hose outlet,
thanks for the input

you can buy water outlet spacers that are like 1" tall that have multiple ports for sensors fyi

where can you get these spacers?

I think Summit or Jegs will carry them.

Block-drain area runs a bit cooler than the water pump outlet side, not necessarily a problem, but I like to know the hottest temp, which is in the heads, thermostat, and outlet side of the pump housing. You could also use a pipe-thread T, or drill & tap the area behind the alternator bracket. The bracket will need a hole in it to clear the sender.