After receiving a box of parts back from the vapor honer, I noticed that the two lower thermostat housings I had are different. One came from a 72, the other I am not sure.

I believe the one on the left is part number 11061-P0300, which the microfiche indicates was used on 1973's.

So I suspect the one on the right, having lighter-duty top and head flanges, is 11061-E3000 and is for 70-72. Can anyone confirm?

What's on your original early 240Z's?

This pic is from a mid-1970 car. I believe it is original. (I have no reason to believe otherwise):

I have one of each type, this one is from #6521, 7/70

And this one is on #957, 1/70. Hard to get a good pic when it's still installed. Both have the Hitachi logo.

Edited Tuesday at 11:51 PM2 days by CanTechZ

The one shown on the left without the base flange is early.

I just noticed something related to the early vs later thermostat housing thing. The water outlet that bolts to the top of the housing, also has early and later versions. This pic is of my 1/70 car, with the water outlet from my 7/70 car sitting loose to the left. The early version has an extra tapped hole, circled in red, that I assume is to mount the bracket for the spark plug leads retainer. I noticed this when changing back to my 55 year old OE Yazaki date coded leads. I'm putting these on for car show season. Lol. I also noticed that my early car is missing the bracket that should go into the tapped hole. @zKars would you happen to have one? 🙂

Here's a pic of my 1/70 before I changed the spark plug leads. If you zoom in, you can see the tapped hole and no support bracket.

And here is a pic of my 7/70 car before I took it apart for the resto. If you zoom in you can see the bracket, and no extra tapped hole in the water outlet. FYI, my 7/70 car is where the OE spark plug leads came from.

Just for fun, here's a pic of my 1/70 (#957) with the 1970 date coded leads. If you zoom in, you can see the markings, sadly they are starting to fade. They do look much better being black. 🙂

Edited yesterday at 02:21 AM1 day by CanTechZ
Added pic

Cool. Seen that hole before on some housings, but never noticed it was threaded. Only ever seen the spark plug holder bracket go under the rear therm housing bolt.

Let me see if I have one

Only 7….

All used, you’re welcome to a decent one

Regarding the LOWER thermostat housing, the conclusion I'm coming to is that indeed, the narrow-flange one is 11061-E3000 and is for 70-72 cars. It seems to have been replaced by the wider/tapered flange 11061-P0300. The micro-fiche seems to support this.

Also here is a pic of the early 21K-mile BAT '71 car with the narrow flange housing.

8 hours ago, Broman said:

Regarding the LOWER thermostat housing, the conclusion I'm coming to is that indeed, the narrow-flange one is 11061-E3000 and is for 70-72 cars. It seems to have been replaced by the wider/tapered flange 11061-P0300. The micro-fiche seems to support this.

Also here is a pic of the early 21K-mile BAT '71 car with the narrow flange housing.

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.

Edited yesterday at 01:05 PM1 day by CanTechZ

I believe that hole on the 73 was used for the temperature switch for the EGR system.

This pic is from 74 260, but 73 had the same thing:

Actually, looking at that thermostat housing you have on your 1/70 is not from 73... It's from couple years later than that. 75 at least.

It's got a thermotime switch and temp sensor for the EFI system.

Thanks for that info CO. 👍