For whatever reason, I can't edit my first message so I'll post another.
I've been watching Leica prices for awhile and, as I mentioned to another member just this evening, they seem to be going up almost daily. For instance, a garden-variety 1950 IIIc with a Summitar lens sold a few days ago for $400 and a IIIa in rather worn exterior condition was bid to $227 and didn't meet the reserve price. I believe it had a 50mm f/3.5 Elmar lens. Still, I consider $227 for a camera in it's condition to be high.
The first IIf model cameras were made in 1951 starting with serial number 451,001. The first 9,000 of a total run of 34,000 were black dial models with 1/30, 1/40 & 1/60th shutter speeds. The red dials (production of 25,000) with 1/25, 1/50 & 1/75th speeds followed with production ending in 1956. With the Summicron lens, the factory code was LOOUN. Other than not having slow shutter speeds, the only other difference between the IIf and the IIIf was the accessory shoe. The IIf had a heavy flat spring held in place by two screws whereas the IIIf shoe had four screws and two pressure bars that held items in place; a more expensive arrangement.
Some of the cameras made in 1952 & 1953 were marked D.R.P. and also G.M.B.H. which is characteristic of later model cameras.
My reference for this information is the book "Leica, The First Fifty Years".
Walker