2008 sierra vmax 6.2 6l80 tuning/ OS issue

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Good day everyone,

I have a 2008 GMC Sierra 1500 Vortec Max that I have swapped a 6.2 6 speed from a 2007 Yukon Denali and swapped the transfer case from a 4x4 truck. (I have modified my 08 harness to act as a standalone harness for the transfer case.) I?ve noticed when doing a data log, my speed is pinned at 255 unless I change it to the transmission or wheel bearing. I also don?t have certain functions like cruise and command start on my truck from the factory. I?m hoping to regain these functions, as this is my DD.I think this is related to the speed reading, but I'm only guessing since I have no codes present other than an airbag sensor and service 4x4, which I believe is related to the VSS wires not having a home currently. I did find a tune on here for an 08 Sierra Denali that ran the same OS # on the ECM and TCM I am currently running. (08 vmax e38/ 07 t43 ) I should have a read file and log file attached I believe the log is running wheel bearing speed. I am no expert any help to advise would be nice thank you.

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I got the service 4x4 fixed for now. My ECM speedometer reading still pinned at 255 and I believe this to be the cause of no cruise control and command start. That’s my analysis not sure if anyone knows if I’m doing something wrong by using my stock e38 for my truck and using the t43 from a separate vin set. I have found other tune files for 08 denalis that have the same TCM ECM OS# am I wrong to think it would be compatible or am I missing something

[DodgeZ]

Was it a 2wd truck to start with?

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it was 4x4 originally. I removed the transfer case harness from the original to Frankenstein it together which seems to be doing the engaging 4x4 HI & Low