Love the toning, obverse very nice, reverse the frontage windows, door, steps, and columns are faded. MS-63 possibly 64.
I went MS-64, great toning and everything is wonderful, think the reverse being faded might just be the normal strike for this year but didn't look in a reference to see, I do like the lunette window as far as it's outline so I think that if it was less than MS-64 that might have shown something making it less clear than it seems here. Just a thought, again did not go to my references to see.
My guide book doesn't say much as to strike details. Except that lustrous coins were not a problem. 5FS 1-10 and 6FS scarce. The coin above does have a mushy center. The steps are nearly full maybe 4 3/4.
Ok, I have a couple of references and maybe you had a 3rd edition MegaRed with the nickel info you gave??? (or basically the same thing but in a different form, i.e. redbook stuff) but also I have the 2nd edition of The Jefferson Nickel Analyst by Bernard A. Nagengast and for a 1948 D nickel, that's pretty much similar for the MegaRed info I mentioned (and what you said) but it also says for this issue that "Much of the issue is struck from worn dies and the coins exhibit flow lines, orange-peel and mushy lettering. Often seen with yellow or golden toning" So, based on this so far, I would say if the coin overall doesn't have a bunch of flow lines, it might be on the 'better side', i.e, a 64 vs a 63 and of course, be consistent with the regular standards as to how many and where distracting marks might be. So perhaps I think it still might as long as the mushy reverse is mild, as in maybe the worn die used was only beginning to be worn? I guess that might be a judgement you'd have to make with the coin in hand.
Also, per my grading guide by coinworlds CoinValues (a book) the Jefferson nickels have this difference between a 63 and 64: 63- may have noticable detracting contact marks and minor blemishes in prime focal areas; exhibits attractive mint luster; good eye appeal 64 may have light, scattered contact marks with a few in the prime local areas; luster must be average to full and eye appeal generally pleasing. Basically I can't really see the luster but I'm not noticing that it is absent or impaired, I'm running on the assumption that the toning is kinda overwhelming me from really seeing the luster or that the luster I see is unavaiable for me to really determine based on the photos here. But I don't also see where it would be impared, which should drive the coin down to a 61 or 62. I don't see the coin as having poor eye appeal or dull surfaces either. What I do see is to me, accepting that maybe with the way the toning is that the surface still has really nice luster, so 64 quality (i.e, it looks generally pleasing to me vs just good eye appeal) and I didn't look hard, maybe I should have, but I'm not seeing really any detracting contact marks, sure there may be some, but I don't see them as detracting, so that's why I went with the 64 vs 63 really, I didn't think the marks should make it a 63. That said, doesn't mean a grading service might not just put it at 63 or less... What do you think? I'm looking forward to finding out your opinion.
Some folks back in the day Technically a 65 at best. The eye appeal and smooth luster change from grader to grader.