Sonnaxs , Transgo and other companies have kits for them and I’ve had real good luck using them, I just finished one up and used the Sonnaxs kit and it worked great
A couple of thing would be to see if fluid drops when you start it , The little gasket(seal ) that goes
on the v/b between v/b and case can fall off or missed will cause no engagment,
I own a trans shop and have rebuilt a lot of them, Very comman to get bad valve bodys from ford, When I rebuild them I dont replace the v/b I install a sonnaxs zip kit in the original one, It will take a lot of driving to get them to relean