On Feb 24, 6:05*pm, Louis Ohland wrote:
* *Preparing to run coolant on my X3, I pulled the coolant plug out,
expecting an NPT thread. It isn't. It's a straight thread, Major
diameter is @ .620, pitch diameter is @ .577.

The Grizzly manual does not even show the plug, which is at the far left
rear corner.

Anyone with the answer?

Here's a table of hydraulic fitting threads, which it apparently
isn't:
http://fittingsandadapters.com/saej5straigt.html

Is the pitch Metric?

jsw