johnny Ainsworth

I read read in an article that in May 2021, GM dropped the DFM/AFM from some of its pickups with the 5.3l engine. Was told to look for RPO code, YK9 to determine if it was made without the DFM/AFM. Does anyone know if GM is still making engines without the DFM/AFM? I'm really wanting the 6.2L, but would consider the 5.3L if I can get it without the DFM/AFM. As a side note, did GM just not chip for the DFM/AFM but left all the internal components the same?

I have a 2005 GMC Sierra Quadrasteer that developed an issue yesterday (maybe in the transfer case). First, I noticed the tow switch did not work. Then after pulling a load of wood home in 4WD High and after unloading the trailer, I noticed the truck would not switch into 4WD high. When 4WD high is selected, it either reverts back to 2WD or switches to AUTO 4WD. I then put it in neutral and switched it to 4WD LOW and that works. So, I put it back in 2wd and drove about 20 miles to get some fuel. This morning, I cranked the truck and again tried the tow switch which didn't work, then noticed my 4 wheel steer was blinking between 2 and 4 and would not lock into 4 wheel steer. Next I tried the 4wd high and it would not lock in. Last I switched to 4wd low and it worked again. Then I put it back in 2wd to back up and my truck lurched backward and made a clunk sound. By the way, when switching to 4wd low there is a noticable clank when engaging and another lesser clank when disengaging. By the way, my pocket OBD2 scanner didn't find any faults. No check engine light. Does anyone have an idea of what is going on to cause this. Prior to yesterday all was good. Any insight would be helpful.