Temperature Sending Unit(s) and Electric Gauges

[leefybeaver]

Hello again to all those smarter than myself. I recently got a 3 gauge electric style cluster from summit racing. I was going to wire it up today. It all seems pretty simple to me however I was wondering about the sending unit for the water temp gauge. The gauges came with sending units for both the oil pressure and water temp. I installed a water temp sending unit to plug the hole in the intake manifold which is the large style sending unit below. The one that came with gauge is a smaller unit, also shown below.

So long story short...Is there and real difference between the two?
Can I used the one I have in the manifold now and avoid getting an adapter (unless there is a secret place I don't know about to install the little sending unit)

That's pretty much it. Thanks for the input.

 

[565bbchevy]

I am surprised the new one did not come with the adapter but I would still use the new sender with the new gauges, the calibration could be different from your old sender and throw your temp. reading off. You could contact Summit and ask if the adapter was supposed to be included and if not you can try a local autoparts store or Jegs since shipping is included in their price.