is there a difference in the 2005 automatic transm9issions and the 2006 automatic transmissions and if so what thanks

 

There is definitely some difference because only the 06+ are approved by DC for use with an exhaust brake. It could just be a programming difference, but I think there might also be some slight changes in the internals.

 

AFAIK, no hardware differences. Programming only.

 

My understanding is that there were a handful of upgrades to the '06 model year trans. The most significant was changing from a thrust washer to a thrust bearing in one area of the gear train (don't remember where). This was done to improve reliability of the trans when used with an Exhaust brake, since the TC is locked up and reverse loading the planetary (helical) gears.

HTH

Tony

 

Then why can't the 05 and earlier just be "re-programmed" to work like an 06+?

 

The ECM's were changed in '06 too! Needed more flash memory to handle the jake and hi idle programming.

TOny

 

The thrust washer changed in the later 04 transmissions and was just much ado about nothing. Lots of earlier trucks running around with EB's having no issues. For the most the 4RE hard parts are unchanged from 05-07. Maybe some different clutch materials and possibly seal designs and materials. Essentially no changes to speak of. The differences were DC would warranty and EB on the 06 up and the addition of OD lockout. All programming additions which can easily be added with aftermarket pieces.

 

Lack of memory for the 10k lines of code to handle the EB brake functions. Mid 05 saw the introduction of the electronic TV control and was essentially an upgraded 04.5 ECU. That addition it could handle but then it did not handle the down shift lockup situations very well. Halfway thru a production year DC was not going to suddenly switch ECU's when they already had them in the pipeline. All about costs.

 

FYI, the high idle was available starting in 04. Even the some late 03's were capable with a flash.