Hot Racing SRVO1337T Steel Helical Spiral Differential Ring/Pinion Gear Set (37t Made by Hot Racing; Hot Racing is a United States based company; parts are sourced from Chinese producers All Hot Racing upgrade parts are direct replacements for stock components; additional parts are not required Hot Racing part number SRVO1337T; UPC 083745451344 This item works with: Traxxas E-Maxx 3903 Brushed, E-Maxx 3908 Brushless, E-Revo 5603 5605 5608, Rally VXL, LCG Slash 1:10, Revo 3.3 5309, Slash 4x4 all versions, Summit, T-Maxx 3.3 4909, Telluride 4X4 trail rig, XO-1