Mike, I see the picture now added to your first post in the thread. All that info is clear thanks to a very thorough cleanup.
Here is a breakdown of what "I think" that info means:
2 = The assembly line at the plant (I think)
E25 = E = May / 2 = 2nd day of May / 5 = 1955 (This is using what we know of general GM casting date codes as far as I know)
GM = General Motors
591953 = SM420 main case casting ID code as noted previously above - 1948-63
T = Toledo (Assembly Plant)
Others will come along and confirm or offer more on my info as they may have more knowledge than I.
Finding and posting the actual "stamped" unit number should help confirm what is listed here. Will watch for further pics and updates.
PS - The good news is YES it will work for you with the needed driveshaft changes!
