The Turbo 400 has no lockup clutch in the torque converter. Therefore, there's no mechanical connection between engine and trans. Therefore, no engine braking. Now when you say GM 400 transmission, you mean the old heavy duty three speed turbo 400, correct?larold;74400 said:Any transmission guys know if there is a way to get engine braking in drive? I have a 6.2 turbo diesel with a GM 400 transmission. When in drive and i release the accelerator and it just coasts which if fine most of the time, but every now and then I hit a hill that needs it.