I have a 5.7 that I am putting in a 39 plymouth. I would like to run factory stock parts to stay on the cheap side if possible.

AS I understand the 2003 ECU's did not control the transmission so I was thinking this may be a good option if I go with a 5 Speed tranny. But if I run a 518 auto I will need something to control the kickdown so I would want the Tranny control, which means either a separate TCU or can I use a later ECU and control the 518 tranny?