You should be able to find a replacement fan. Look for "squirrel cage exhaust fan".

Thank you! What kind of professional installs that?

It could be DIY depending on your skill level. I’m assuming the are a few mounting screws for the fan that would need to come out and then connecting the wires for the new fan. Being from the 70s, it’s probably not plug in. Just be sure to cut the power to it.

As for professional……. electrician, handyman, etc.

Thank you!

I wonder what the flow rate of that assembly is. Does that unit burn charcoal? If so, there is a carbon monoxide hazard that should be addressed with a significantly higher flow rate. If electrically heated, then the grill fumes may only be burned fat, but the hood still needs a flow rate commensurate with the fume generation. I wouldn't want less than 180 ft/min velocity at the entry aperture, which is about 1000 CFM, calling for adequate MUA and a blower rated perhaps as high as 1500 CFM at zero static pressure.

I'd seriously consider a Wolf Outdoor Wall hood (page 153 of the 2023 Wolf Design Guide), or some other supplier's equivalent to ensure envelopment of the rising and expanding cooking plume.

Thank you so much for your input. Still not sure where to start with is. It’s 106 in San Antonio and grilling outside has been quite an experience

I was referring to using the outdoor hood for indoors. In any case, if you are moving 1000 CFM indoors, you not only need to heat the MUA in the winter, but cool it in the summer. The plot below shows the needed heating or air conditioning load as a function of difference in temperature between indoors and outdoors. (Click to expand.)

An area where one doesn't really want to embrace "better to ask forgiveness than permission" is interior safety. I think you need to consult with your local code enforcement department. You could be in a position where any fire resulting from an out of code device allows the insurance company to escape responsibility.

Does that assembly have any way to filter grease before it makes its way up the ducting?

There is still the question of whether it uses charcoal, gas, or electricity for grilling. I would be surprised if using charcoal indoors could be made complaint no matter what ventilation was provided.

Thank you!!!