Do I need a transmission

Hi all I'm back with another one this
time it's wether or not I need a
transmission. Rpms rev up and down
when in park and neutral and revs
high when in drive. Now it just revs
but can't drive or reverse mind u I
need a center gasket because I just
replaced the catalytic converter so I
have loud constant reving noise. I
noticed that my transmission fluid
was blackish and very low. Not to
mention I Had white smoke come
from the hood and underneath the
chassy. Thanks in advance. I poured
a quart of merc dextrin 3 and still no
motion...help... Thanks again. I'm
stuck on the road.