Its not a theory. The Allison Duramax automatic transmission has been on the market for about 8 years now. Unlike previous automatics, it has an extreme-duty life expectancy of about 200,000 miles before requiring removal and overhaul. The Spicer 5-speed manual transmission that it replaced has a 250,000 mile life expectancy, but it needs a clutch rebuild every 15 or 20 thousand miles. Also, the newest generation of electronically controlled 4 cylinder diesel engines perform better when the engine management system can control the shift points for the automatic transmission to match engine output, RPM's etc. This wasn't necessary with the older PowerStroke and Cummins engines from the 90's. If you dont believe me, Tieguy, ask one of our mechanics.