Hello,

Can anyone tell me the model of t-case in my truck? (See my sig). Also, does anyone know the reduction in low range, and the first gear ratio of the Allison?

Thanks!

transfer case should be 263c

Did a little research - it is indeed a New Venture Gear (NVG) 263 transfer case. Reduction in low range is 2.72:1. The first gear ratio in the Allison is 3.10:1, and the diffs are (of course) 3.73:1. This results in a total reduction (crawl ratio) of 31.45:1. Not bad at all when you consider the torque the Duramax makes (doesn't need much multiplication to be effective in low range).