mboulais,
I was interested in purchasing a Renault tractor but someone got there before me. While I was looking for information a few months ago, I ran across this:
This information is a little dated but it may help: Renault tractor parts, Quebec 450-427-0955 (1999 phone number).
Also on Yesterdays Tractors concerning the Renault N70 a poster from Germany said: "The Renault N70 was built since Sept. 1960. He's got a 35 HP MWM (Motoren Werke Mannheim) engine with 2715 ccm, air cooled German item, may be in America. It is a very rare tractor. Renault also built tractors for an American plant, I believe Oliver or Allis-Chalmers, wheelbase 185 cm, weight 1623 kg, MWM engines".
The post was from 8/2001 and there was a little language translation problem.
I have no idea if this is any help, but it may be a place for your friend to start.
Regards, Mark