Freeze Plug??

[sbalgach]

Hi, I have a '75 Chevy C-10 with a 250 6 banger. I just went to start it after it sat idle for all of last winter and I think I blew out a freeze plug. It is on the Driver side of the engine but the leak (severe) is not from the block but it seems to be from the intake manifold??? It is just under the "sending unit" for the engine temp (I think). I have limited access to the hole. The exhaust manifold is just below it.

Is there a freeze plug there or is the manifold history? How can I get a new plug in there?

Thanks in advance,

Steve