geonc,
The Alf4 code is for a dpc-203 '96 truck. The TDEO code is for a dpc-202 '97 truck. Better double check, you can have any of these codes flashed to your dpc-203 PCM,
AUG4
ALF6
BEG5
AUG2
AUG7
MLE0
SOD4
SOD3
AUG6
SOD2
AUG1
SOD1
ALF5
GOB0
BEG8
BEG6
SOD5
ALF4
ALF0
ALF1
ALF2
MLE1
AUG5
AUG0
AUG4
ALF6
BEG5
AUG2
AUG7
MLE0
SOD4
SOD3
AUG6
SOD2
AUG1
SOD1
ALF5
GOB0
BEG8
BEG6
SOD5
ALF4
ALF0
ALF1
ALF2
MLE1
AUG5
AUG0
AUG4
ALF6
BEG5
AUG2
AUG7
MLE0
SOD4
SOD3
AUG6
SOD2
AUG1
SOD1
ALF5
GOB0
BEG8
BEG6
SOD5
ALF4
ALF0
ALF1
ALF2
MLE1
AUG5
AUG0
AUG4
ALF6
BEG5
AUG2
AUG7
MLE0
SOD4
SOD3
AUG6
SOD2
AUG1
SOD1
ALF5
GOB0
BEG8
BEG6
SOD5
ALF4
ALF0
ALF1
ALF2
MLE1
AUG5
AUG0
Hopes this helps!