Do think you could post some pictures of the coupling hubs and the spider and provide some approximate measurements? If you can do that I'll help you chose which spider you need from McMaster.
Unless your hubs are totally trashed, which I doubt they are, you don't need to replace them. I'll make the assumption that the hubs are keyed to the shafts and if they are don't get too wrapped up about how many setscrews are in each hub. Some manufacturers put only one setscrew in the hub and it's directly one the key, that way you don't booger up the shaft with the second setscrew.
As a woodworker if you can measure the length of a shelf that goes in a cabinet you can make the measurements needed to pick which spider you need. We ain't going to the moon here.
Confidence: The feeling you experience before you fully understand the situation