Cadillac Repair: 78 CADDY, vacuum modulator, vacuum line

Question
MY TRANS WILL NOT SHIFT STAYS IN FIRST GEAR ONLY I HAVE CHANGED THE VACUM LINE AND RUBBER PIECES WHAT COULD BE WRONG

Answer
Can you feel a vacuum at the vacuum modulator on the trans with the engine running ?.

Sometimes you can feel a vacuum but it is not enough vacuum due to the metal line has small rusted pin holes in it where you have attached your small pieces of vacuum line to this metal pipe at each end.

Try putting rubber vacuum line from the engine all the way to the trans modulator and make sure that yu use approx the same size inner diameter vacuum line as is the steel line or you will not get enough vacuum VOLUME in order to make the modulator work.

There is also a possibility that your vacuum modulator is no good.