97 freightliner rear axle

Try shopping for differential and axle separately. Junk yards may pull a lot of diffs to have them ready to sell. You might also try Steve's Truck and Equipment in Scttsbluff, NE. About 7-8 years I got a lot of parts for my Century. They have their scrap yard in Mitchell, 10 miles away. And they had a lot of Freightliners there. I was allowed to pull parts myself.

 

Never heard of a 3.07. Why can't you just buy the axle assembly and swap the ring and pinion out? Assuming you're looking at salvage yards I wouldn't chance running it without taking it apart and checking it anyways.

 

I found this list . You can look for the model number and what series for your ratio.

Rebuilt Eaton Differentials, Replacement Parts & Manuals 877-776-4600 (globaldrivetrainsupply.com)

Not sure what your looking for. single or twin screw.
Meritor RR20145 Rear Differential | Carrier Assembly for Sale (vanderhaags.com)

Good luck