Replacement thermostat for 70HP doesn't match original?

[Chaparralbob]

I bought a replacement thermostat for my 1990 70HP Evinrude. It is the Sierra equivalent for the part number shown on the BRP website. The new part does not look like the old "vernatherm" style that was in the motor. The rubber seal that is shown on the BRP webpage doesn't look anything like the old part. I bought a retaining cup and doughnut-like rubber seal, also the parts shown on the BRP webpage, but they are too small to fit in the engine block. The old part uses a tapered spring, and the rubber seal is larger than the recommended part. On the old part, the rubber seal slides onto one end of the vernatherm housing, and has a narrow metal ring that goes in the engine block.

I have looked a couple of years either side of 1990, and can't seem to find the thermostat that looks like mine.

Does anyone know what I might have?

Thanks for any help with this.