This article is brought to you partly for curiosity and partly for history The 43/13 final drive ratio was run in the pre-production MGA at Le Mans in 1955. This was jolly good for ripping down the six mile long Mulsanne Straight at full chat in a stripped down aluminum bodied car with cut down windscreen and somewhat more power than your ordinary street machine.
There were apparently more than just a handfull of these gearsets produced in the mid 50's. Some have been reported used in more recent times for long track racing MGA's. This one came up for auction on eBay in early December 2006 in new and unused condition with a winning bid of £206.55.
I have saved these pictures from the eBay ad for historical purpose, just so you may know that the thing is real.