Recently acquired a 1992 manual 4.9 liter and I went to replace the transmission fluid only to realize some boob had welded a giant 1 1/2" bolt onto the fill aperture. Drain plug is still intact and my question is this: after draining the fluid is it OK to add the correct amount of fluid through the top opening for the shifter bar? Or is there a better way? Thank you

 

Just figure out the correct amount and get it in there however you can. Gotta wonder why someone would do that, but as long as you have the correct amount in there, that's the best you can do.