While Allison TCM's do accept tunes, we have found that our builds work great with the stock strategy. It is advisable to leave transmission tuning stock. If you have transmission tuning, please advise us when purchasing a transmission.

Start by checking all power and ground connections to the TCM, as well as scanning for any communication codes or related issues. If no faults are found, or scanner can not connect to TCM, keep in mind that Allison TCMs are known to experience failures. A faulty TCM is always a possibility and may need to be replaced.

No, we do not. If you pull up the ratios for the final gears for the 5 & 6 speed models, you're only gaining around 100-200 RPM drop by going to the 6 speed (a difference of .097:1); which is negligible.