This is the unique crown and pinion with the 3.45 11/38 Ratio
Manufacture - AVT Technology company from Russia. They produce top quality parts for the differntials and gearboxes. Quality is one of the best you can find.
To install it, you will have to machine your stock differential on 2mm. Please look at the drawings on the fourth photo.
Stock size iz 33mm (bottom part of the photo), you need to receive 31mm (upper part of the drawing) for the correct work.