Do you have a picture of the packaging? Two easy explanations:
A: The box is for a Classic II upgrade, but someone stuck an LC FPU board in there instead. (According to Apple the Classic II *does* have a slot that's intended for an FPU upgrade, and according to several sources some were made. link)
B: (Pure speculation) A vendor sold an FPU upgrade for the Classic II that involved packaging an LC FPU and an adapter board? (And the adapter is missing, possibly still stuck in the slot of the Classic II this was pulled from?)
There are passing references to FPU boards that ran asynchronously to the main CPU but a quick Google didn't turn up a specific product name. It could be that (it does appear to have a crystal onboard, and... do you suppose that "alt/sys" jumper might select whether the crystal or the motherboard clock is used?) or it could just be that when the board was populated 16Mhz FPUs weren't any cheaper than 25mhz ones.
A: The box is for a Classic II upgrade, but someone stuck an LC FPU board in there instead. (According to Apple the Classic II *does* have a slot that's intended for an FPU upgrade, and according to several sources some were made. link)
B: (Pure speculation) A vendor sold an FPU upgrade for the Classic II that involved packaging an LC FPU and an adapter board? (And the adapter is missing, possibly still stuck in the slot of the Classic II this was pulled from?)
There are passing references to FPU boards that ran asynchronously to the main CPU but a quick Google didn't turn up a specific product name. It could be that (it does appear to have a crystal onboard, and... do you suppose that "alt/sys" jumper might select whether the crystal or the motherboard clock is used?) or it could just be that when the board was populated 16Mhz FPUs weren't any cheaper than 25mhz ones.