28 and 24 are exactly what I ordered from the ipl. I have no idea how I got an inner spike from an 064, but I do remember the bags that the spikes came in had the correct part numbers on them.That's all backwards. Your inner spike came off of an 064, why its on your saw I don't know.
There isn't an outer spike made for the 460 that will match that, it's not possible.
Order #28/24 and you'll be all set.
Felling dawgs are so over analyzed on these forums and people chime in that have no idea what they're talking about throwing numbers around and make it 10x more confusing.
It sounds like an inner spike for an 064 was put in the wrong bag.