Definitely a model T ignition coil. Backstory to me playing with a brand new one: I guess it was more than 30yrs ago and apparently they could still be purchased new. Sold as a "model T ignition coil". They were used in cattle prods or similar.
A bloke who ran a youth group in a local church sourced one and asked me to help him set it up in a fun&games "electric chair". I experimented with it, using a 6v "big Jim" lantern battery as power source. After the (previous post mentioned) testing in a HV testing/standards lab where I worked at the time - I refused to build it into any device for "fun" use.
Not that I was prudish about silly/shock games at all. Did get up to the usual games like charging a capacitor from a fluoro light with a 500vdc insulation tester and tossing it to someone "here! Catch!"

