Ithaca Flues 4ESBT

[Frank Good]

Ok not looking for discussions on value or should I say lack of collectible value. I'm just curious about the stock on this gun. The same fellow I bought the 5E Knick SBT from had this and he thought this was a 5E as well but I informed him it was a 4E with what I am certain is an incorrect stock? I originally passed on the gun but after throwing a real low ball figure which he accepted I bought it. The picture he sent of it was horrible and I was not expecting the gun(aside from the oddball stock) to be in the condition it was. I've looked it over so many times and have to say whoever changed the stock did a great job of fitting. It looks factory fit however the checkering pattern and field dimensions drop suggests to me someone fit a Flues SxS stock to the gun if that is even possible? It definitely has the pistol grip shape and checkering pattern identical to a Flues SxS. Oh and serial # puts this Flues at a 1917 date of mfg. I will probably get a letter for it from Cody to see if they have records of the original order specs.
What do some of you more in the know members think?