[Ricky2022]

2006 6.0 powerstroke. Just recently my driveshaft bolts backed out on the highway and broke my 4wd extension so I bought a spare trans and used that one and the output shaft (it was good) put it back together and now it won’t do over 40. I have no codes other than MAF and fan speed circuit. It’s a built trans with under 10k. It shifts through all the gears and hits O/D around 20mph. Then by the time I hit 35 I’m almost revved out. Shifts are a little jumpier than usual. It has a brand new converter as well. Also in first/second it takes more throttle to get it going. Like it grabs and let’s go and then grabs etc. Trans fluid is good not burnt. Help please

 

[1999f-250superduty]

Sounds like your transfer case is in 4low 🤔

 

[Ricky2022]

Sounds like your transfer case is in 4low 🤔

Didn’t even think about that since there is no light on and it’s a manual t-case

 

[bismic]

What are you using for a code reader?
Could you post the fan speed code number?