What did it grade? That's the only way to know for sure. In all likelihood, the answer would be no...don't resubmit it. It seems like back in the old days these slabs were popular to resubmit these old slabs because you could get an upgrade. But, by now all the old slabs have been picked through and those that would upgrade have already been resubmitted. The one's left are coins that either probably wouldn't upgrade or might even downgrade...so it is likely that you wouldn't get the grade bump you wanted. That said, what did this coin grade? Without knowing that, there is no way to give you advice.
Have you had this coin in your possession since it was graded? Also, what did it grade? As for the VAM possibility...I'd have to look in one of my books which I don't have on hand right now.
You still need to answer the question of what it is currently graded for us to answer your question about whether or not it should be re-submitted.
I would say it's the VAM 10 (or 50, but according to VAMworld it's been suggested they're the same die pair). The coin looks like a 64 too me, not a 63, but there isn't a big price difference between 63 and 64. So I probably wouldn't resubmit it unless you wanted the VAM # on the slab, then I would say you might as well take a shot at the regrade.
I've seen 65s that look worse, but my eyes aren't the best. I think it should make 64, but might not be worth the cost. Maybe you could send it in as a 65 minimum grade and keep your fingers crossed.
Could you point out the reasons for saying that you think it's a slider? I am curious as to what a slider would look like, and the characteristics that would identify one.
I don't see that it's an AU myself, but I'll be the first to admit I could miss it. I did see the hair above the ear, but I attributed that to strike not wear. I see something funky on the cheek, but it's above the area where wear normally occurs first, and it just doesn't look like a wear pattern to me. The eagle's breast appears fully struck and I see no wear there.