What kind of flywheel is this?
 

I just acquired this flywheel and wondering what kind is it? It weighs about 12.6 l bs and doesn't need to have the counterweight.

Thanks in advance

I'm not sure, but it is interesting that there is no step on the flywheel surface. I think this might cause issues with clutch engagement.

interesting....................

yes, very interesting, indeed, and I also have to agree that you might run into problem with the clutch engagement. Having the bolting surface at the same depth as the engagement surface is like having the clutch disk worn by that much. I'm just throwing numbers out but for example if the oem step was 0.010" and now you have a flat surface, it is like your clutch disk have been worn by 0.010". So the pressure exerted by the the pressure plate have been reduced by that much

Does anyone have measurements for the stock flywheel (bolting surface and engagements surface say from the back of the starter ring)?

definatly the stock flywheel that has had the shit resurfaced out of it. the counterweight is built into it.

It is the hairless dog of the clutch world.

Then my next question is who would know if it is useable?

i would definatly not use it, too risky. the runout on the flywheel is 0.2mm and that looks way out of specs.

I pulled this off the Mazdatrix site. It's not the same but doesn't it seem like a machined oem?

the picture you have from Mazdatrix is a picture of an aftermarket flywheel that will require an automatic rear counterweight to work.