traskrover

Hello, i have a 1990 SE v6 4x4 with the automatic trans. Well it makes a real "corse" sound when engaged in drive and continues to make the sound until it shifts to 2nd. gear. Then it goes away and the trans shifts/operates perfect. I also have completely lost reverse. Any idea what the grinding noise could be? it is definetley coming from the trans, and sounds like a gear or something. Also any good links to posts on trans removal and install on this forum, looks like it is coming out either way eh?. 144k and original trans, but looks like it was neglected, fluid was nasty last change. thanks