Curious Sprinter Tech,
Are you sure about this?
Here's a photo of the MOPAR Rear Differential Fluid most recommended for '02-'06 T1N Sprinters:
http://www.ebay.com/itm/SPRINTER-AXLE-DIFFERENTIAL-LUBRICANT-OIL-MOPAR-OEM-/330355238354
You can see that it says "Sprinter" right on the label!
For the later NCV3 Sprinters (906 series NAFTA) the MB BEVO 231.2 Page 2 says
for 906 (NAFTA Sprinters to use MB BEVO 235.8!
Here's a link:
http://bevo.mercedes-benz.com/bevolisten/235.8_en.html
No where in all of this MB official information can I find any reference to
"75W-140 synthetic Gear oil".
All of the above indicates 75W-90 synthetic hypoid oil or 90W hypoind gear oil.
The MOPAR product may not be synthetic as it carries no MB approval number, but
it was recommended lube for Dodge T1N Sprinters ('02-'06) and used by most knowledgeable
Dodge Sprinter dealers.
The later NCV3 Sprinters (906) all need "synthetic 75W-90.
Hope this helps,
Roger