I have a car w/ a 1.25" freeze plug on the rear of the cylinder head leaking. Can't drive in a new freeze plug in the car...would have to pull the head.

What type of expansion plugs have you used and had good luck with? This is a daily driver type car so I hope this fix will work for a good while.

The copper style expansion plugs look like they'd be a better long term solution than the rubber style.

Suggestions?