The similar P4452978 # in my catalogue I have here shows the closest I could find but still not your crank.
You have narrowed it down enough it seems to know its a sweet piece.
I’m liking the 340 mains on yours. View attachment 1716071298
I have the same book and saw the 978 crank but no 976 that is why I started this post. The two digit difference should have tipped me off but it would have been a guess.
