If you want an accurate history of Oliver Tractors you should get a copy of Larry Gay's book "A Guide To Hart-Parr, Oliver and White Farm Tractors 1901-1996" You should be able to get one on ebay or through the publisher.

American Society of Agricultural Engineers (ASAE)
2950 Niles Rd.
St Joseph, MI  49085-9659

800-695-2723
269-428-6324

Hope this helps!

--Marc--