I have a European spec. 945, so this may not have ever been sold in the USA, but here goes:
The 945 is a B200F engined, manual M47 gearbox model, non ABS. I've just checked the back axle which still has the label, but doesn't tally with any of the info. I've been able to find so far.
The label has:

3.91 NR. 1216363
FABR NR 100692

So I guess that is 3.91 ratio, but any ideas what the other numbers might indicate please?

I am thinking of replacing the diff oil with Mobil 1 synthetic 75W-90 as it has never been replaced so far! Both the fill plug and the drain plug needed a nut welding onto them to get them out - they were really seized up, not surprising after 24 years.............
Diff is fine by the way, not noisy, and the oil had no metal in it and hardly discoloured.

If anyone can help with the axle ID please let me know, thanks,

OwenF