from memory it's a nut and then very tight if you don't have a puller it may be as well to let a garage do it rather than cause some damage
That is correct if it is the arm that needs removing, but, if it is only the wiper/rubber assembly, it might be the type that just "snaps" into the plastic carrier, so should be able to "snap" it out, why not buy the correct wiper and have a look at it before breaking the old one or its carrier?
There would probably be two different types of wipers on these cars, early ones - maybe, had the traditional bridge type wiper like old style windscreen wipers - the later ones - maybe had Aero wipers that had a solid plastic carrier.