I have a 69 with a ZZ4 crate in it. I have just completed installation and wiring of the original console guages...Does anyone know if the CG-19 (original sending unit) will work in this crate motor? Thanks!

Yes

Great, I've got one due in from Rick's tomorrow! Thanks!

Actually Steps, unless he uses a adaptor, it will not fit into the head. I'm pretty sure it's too large. I had to mount it on top of the thermostat housing on this ZZ3.

http://i55.photobucket.com/albums/g136/Caman355/244-1.jpg

ZZ4 uses the smaller thread size too

http://i55.photobucket.com/albums/g136/Caman355/MVC-001F-44.jpg

I assumed he would have the common sense to fit an adaper if required
Rather than just dropping it in the hole, then when starts up water go every where.

Actually the problem he is going to run into is an original sending unit it too large for the ZZ4 head. He would need an adaptor to go from small to large and then he's moving the unit out further from the head. Not the best way to go. I'm sure he'll figure something out.

I will have the sending unit today and take a look at size difference tonight...any idea where to pick up an adaptor?
The only reason I am looking at installing the new unit is due to the fact that the existing one that came with the ZZ4 has a totally different type of connection on it, and even if I got that to work I'm not sure it would work with the OEM gauges?

2 problems with using a adaptor. 1 is it moves the sending unit further away from the head and more out of the flow. 2 is now your sending unit will probably hit your header. As you can see in the pic above, there is not much room. Maybe your situation might be different. If you want to try it, you can probably make one up at your local Ace hardware.
My ZZ4 didn't come with a sending unit so I don't know what comes in them now as far as working with an OEM gauge. You can see in the pic below, it just came with a brass plug.

http://i55.photobucket.com/albums/g136/Caman355/46.jpg