I backed out of drive way when I shifted to drive nothing doesn't matter where I put the shifting lever can't go into drive. And I just had the transmission serviced a month ago

Check linkage between shift lever and gearbox. Check shift lever for internal damage.

run the fault codes to find the problem sensor
could be TCM, TR sensor or VSS sensor

check the level of the tranny fluid, if its super low it won't go into any gear cause its a hydraulic ran system

Doesn't matter what gear it's in when you install it. Are you sure you got the shift lever installed right? With the truck not running, can you move the shifter around into all gears? If not, either the shift lever is not installed right, or the transmission has an internal fault. If you can't shift gears only when running, the clutch is not working. On Ford pick-ups with the clutch slave cylinder inside the bell housing of the transmission, best practice is to replace the slave cylinder along with the new clutch.

Put the vehicle in Park, disconnect the shifter from the shift lever on the trans, adjust the linkage or cable so the connection is clearly a slip in/on connection and tighten things back up. Hopefully this will solve your non-reverse. As for all the gunk and metal shavings, friend, you better have another tranny standing by in your garage when this one stops working completely.

push down on the shift knob to get it in reverse

O/D Off means that you pushed a button on the shift lever and effectively "disabled" overdrive. This mode is normally used only when towing something fairly heavy or in some very slick snow or icy conditions. To get the light to go off and put the van back in overdrive, look for the small button on your shift lever and press it in while driving or in park, doesn't matter as long as the car is running.

Things haven't changed much...look on top of the transmission in the engine compartment and look at the shifting linkage. Look for anything that could be interfering with the shifting. One linkage is the cable to the Shift Lever and Rod that goes down into the transmission. Remove the cable adjustment screw.
Move the shift lever rod towards the front of the Van into the Park Indent Position. Place the Driver's Position (Dash) Shift Lever into Park and then reconnect the Cable to the Shift Lever and tighten down the cable adjustment screw to 70 in-lbs.
Check operation's
Let me know if this helped, or if you have any additional information, questions of problems, Feel free to contact me at FixYa.com!

There is a solenoid that keeps you from putting the car in drive if you don't have your foot on the brake. There are several things that can cause the solenoid from working. You may want to start looking there before replacing a cable

Change the shift cable (cable from shifter to transmission) Also spray some WD40 on the shift linkage on the trans and work it back and forth to loosen it up before you put the new cable on. Good luck