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1996 3.0l Ranger/Mazda B-3000 used a 4R44E automatic
Is this your first automatic install?
If so...........did you seat the torque converter inside the bellhousing BEFORE bolting the transmission to the engine?
It seats with 2 or 3 clicks as it slides in more, locking into the input shaft and front pump
If not then you may have broken the front pump inside the transmission
Front pump makes transmission go, no pump no go
You can test if pump is working by checking transmission fluid level Engine OFF, then checking it again Engine ON, it should be much lower engine ON if pump is working