How much Mercon to fill the 4R100 Trans to Fluid Capapcity? Also do I need to add fluid to the TQ before reinstallation? I am completely drained due to a bad front seal and trans R&R.

 

You don't need to add fluid to the torque converter before installing. It will take about 18 quarts to fill the trans.

Add 8 quarts to the trans and then run the engine for 90 seconds, no longer. Use a watch. Shut it off and add 6 more, then start the engine again. Run the engine again, but leave it running. You probably will need to add four more, but go slow. It's hard to read the dipstick and it's a pain if you overfill it.