HELP!! 742 Sure Grip Spider gear needed!!

Alright... I'll bite..., is there a difference in the "spider gears" between a "741", "742" or "489" case?
I've been under the impression that the only difference was the pinion.
I honestly don't know, but I do have a really nice set of "spider gears", I don't know what case # they fit. They've been sitting in a container filled with oil for a few years.
They're yours for the cost of shipping, either way.
I can take pics, save my time and yours, let me know.

Giles