3 Domains with similar website - Canonical tag?

Hello everybody,

I'm having the following situation, I am not deeply familiar with SEO, thus I'm looking for help. So please be kind and bear with me :)

Following situation I've got one website (technically), that serves images / videos and texts blocks depending on the domain. The texts are very similar and sometimes only one or two words change. But they are not identical, but like 90-95% of the texts are the same.

Examples

1. domain-a.com -> text blocks for car type = SUV
2. domain-b.com -> text blocks for car type = limousine
3. domain-c.com -> text blocks for car type = truck

The questions

• Shall I put a canonical tag in the HTML head?
• If so, shall they all point to the same domain, e.g. domain-a.com?
• Is there any other situation / recommendation I should consider?

Side node If important information: domains are redirecting from domain-a.com -> www.domain-a.com etc.

Thank you very much for your support and help.