Buchanan Body No. 55

This fine looking Buchanan belongs to David Hutton in NSW. David is looking for some history. This car lived a good part of its life in SA. There are a few South Australian Buchanophiles. Maybe someone can throw some light on its past. Below is a letter from David. Hi,
I own the above vehicle. It appears to be on a MG TD chassis and runs a MG engine/gearbox/rearend of that origin. I know very little of its past except for when I bought it the seller had purchased the vehicle in South Australia.
If anyone can supply any information I would be most grateful. The car is on full NSW registration and fairly original except for seats (early MGB I believe).
David Hutton.