Early/late thermostat housings

14 hours ago, CanTechZ said:

After looking at some '73 240Zs on BaT, and your supporting info, I have to agree that you are correct. Also I noticed that "thick flange" one also has an extra fitting hole on the front, to the left of the temp sensor hole, that does not exist on the early thin flange housing. On my 1/70 that fitting hole has been plugged. Anyone know what it should plumbed to on a '73? Here's a pic of mine, fitting hole circled in red.

So it's still not really clear just when the factory made the switch over to the wide-flange 11061-P0300. The fiche indicates either were possible up to 6/72.

But the wide-flange 11061-P0300 does NOT have the extra hole @CanTechZ mentions. The housing with the extra hole showed up on the '73 models and is part number 11061-N3300. And it changed again for the L26 is is part number 11061-N3600.