Just swapped in a 5 speed w50 in my 77 pickup from a 78. It had a 3 Speed a40 in it and it went out. Long story short, checked everything, plugged in all wires and now the starter wont engage, like its not even getting power. Ill post pics if anyone wants them and ill make a detailed how to and the issues i ran into on another forum. PLEASE HELP ME.

 

I'm sure you checked your connections did you make sure the solenoid clip the small female connector is nice and snug on there and that the terminal is clean have you checked for voltage from the positive connection on the starter. Or take a some wire connect it two the positive battery strip a little of the other end and touch the male connector on the solenoid ..