After the Newegg X2 3600+ shot up to 76.00, I began looking on Ebay to see what they had there in terms of dualcore AMD CPUs. I found a nice selection of Socket 939 dualcores, but noticed that there were Toledo based X2s, as well as the Manchesters that I know.
 
I went to Wikipedia, and noticed that the only difference I could tell between the two is that the Manchesters have "E4" stepping while the Toledos have "E6" stepping. One would think that the "E6 " stepping is newer, but I noticed also that the Toledos seem to have been released prior to the Manchesters.
 
So, what is the difference between a Manchester and Toledo based Athlon X2?

Toledo = 1mb L2 cache per core
 
Manchester = 512KB L2 cache per core

Manchester was released as X2 4200+ and 4600+ with a total of 1 MB L2
Toledo was released as X2 4400+ and 4800+ with a total of 2 MB L2
 
You may also come across 3700+ single-cores with Toledo cores which are defective dual-cores.

What is the difference between a 3800+ X2 Toledo and 3800+ X2 Manchester?
 
Wikipedia says they both have 512 Kb L2 cache per core.