Maybe I should start out by saying why I'm posting this and then asking the relevant questions.

The first PC that I bought for myself had a "hybrid" 3/486 motherboard that could accept both 386 & 5v 486 CPU's (there has been numerous posts about these type of motherboards and that, for example, some of these motherboards' VLB slots only worked with 486 CPU's).
My motherboard utilises the Opti 495XLC chipset with a 386DX AMIBIOS onboard.

A couple of years ago (after removing it from storage), it didn't want to boot up anymore.
A while later, I came into posession of two 386DX AMIBIOS chips and swopped the BIOS chip out.
Sure enough, the motherboard booted up, but wouldn't boot post the main memory count down screen.
I realised that the BIOS chip was from a motherboard that utilised an ALI chipset and not an OPTI chipset (which made sense), but at least I knew what the source of the problem was.

At this point, I'm trying to obtain a replacement 386DX AMIBIOS for my OPTI 495XLC motherboard, but I've seen similar hybrid motherboards that utilises the Opti 495SLC and Opti 495SX chipsets.
Finding some of these Opti based motherboards (preferably a "defective" one, so that I don't have to pay a fortune for it), is also proving to be challenging.
What is also strange is that some of these motherboards has a 486DX AMIBIOS and not a 386DX AMIBIOS.
I've read that BIOS chips from motherboards with similar chipsets should work with each other.

Coming to my questions:

What are the differences between the Opti 495SX, SLC & XLC chipsets?
Will a BIOS from a motherboard with one Opti 495 chipset work with a motherboard that has another Opti 495 chipset (for example, will a BIOS from an Opti 495SLC chipset based motherboard work with a motherboard that has an Opti 495XLC chipset)?
Does it matter whether the BIOS states 386DX AMIBIOS or 486DX AMIBIOS, if they are from an Opti 495 based chipset?