Alrighty-o, so, Update number 2:
I got in contact with the owner again and asked him about the leak, he said it was comming from the "Shaft seal from the side of the gearbox".
Not sure if that helps in any way, but either way, I doubt I'll be able to get much more into on it until I see the car by myself.
On that note, I talked with my father and it seems like it would be possible for us to go and see/buy the car the next weekend, likely on the 16th (if everything goes right).
If that happends, I'll do my best to answer all the questions as soon as I bring it back home!
Oh, also, the owner mentioned that the repair on the car was documented on a facebook page so maybe it'll come in handy:
Project R4. 282 likes · 1 talking about this. Project R4 zajmuje się odnawianiem starych samochodów, główną marką którą się zajmujemy jest Renault a model to oczywiście Renault 4, zapraszamy �
www.facebook.com
You can sort-of see the oval plate there, but aside from "R1125" it seems quite illegible to me.
Also also, here is the link to the original listing:
22 900 zł: Uwaga, ciekawa oferta nabycia pięknej Renówki z 1973 roku Ogłoszenie wystawiam na prośbę mojego znajomego, jest to R4 które od 2019 przeszło gruntowny remont podwozia (naprawa ramy wraz z zabezpieczeniem dołu + wymiana
sprzedajemy.pl
There are a few photos of the insides of the car (including one of the plates under the bonnet), so I imagine it might come in handy in trying to figure out what it exactly is.
I'll keep you all updated if anything new comes up!