The interesting thing about the case is that as recent as 5-7 years ago people have been finding money with serial numbers matching the ransom payment. More over, the FBI confirmed that the ransom money never entered the circulation again. Honestly, after doing some random research and listening a few radio shows on this subject, it almost seems like Cooper accidentally dropped the money bag but survived the actual parachute landing.
Source? I do not recall anything about DB Cooper in regards to the money other than the money that was found in the river in the 1980s and was later sold in 2008. And that has been the only source of serial numbers matching the ones found in ransom.
"The letter which precedes the numbers must be the same number that you saw identifying the Federal Reserve Bank. The last letter of the serial number or suffix letter identifies the number of times that the Bureau of Engraving and Printing used the sequence of serial numbers: A is the first time, B is the second time, C is the third time and so on. With one run for each letter of the alphabet (26) and 32 bill per run, there are a total of 832 bills per serial number."
The site you quoted seems to be something that someone copied & pasted and slapped together. When the author says "32 bill per run", he seems to imply that the whole sheet always has the same serial number. Well, it certainly is not always true as you can see in this high-res photo of an uncut sheet of 1985 bills:
A much more informative site which seems to be someone's labor of love says there is an exception with old Nationals "in which all notes on a sheet had the same serial number and had to be distinguished by their plate position letters." Although he's not explicit, my reading of that site suggests that modern bills (including the time of the D. B. Cooper incident) should be unique.
