Hello I woud like to help you
I know you said it differential was in pieces, but on the side of the ring gear there should be some numbers stamped in it these will be the teeth count for each gear. For example if you had 44 11 then your ring gear would have 44 Teeth and your pinion gear would have 11 teeth. so your ratio would be 44/11= 4.00:1. If you can find the stamp numbers then you'll know your ratio.
Here's some more information I cannot guarantee that this is 100% correct
Year: 2001 Suzuki VITARA Rear Axle
At worst case if you cannot figure out the front ratio you might have to pull the rear carrier, from the rear axle to be 100% sure of the correct a ratio.
I hope this helps you please let me know if I can help you further