Subaru legacy 1998 2.2 L sedan

Hello All!!!

So I have a legacy all stock besides a D/T muffler a
shop threw on for me. I have a knocking sound
coming from the transaxle on the transmission
side. It started after I replaced the front spindle I
took out the axel and had slammed it back into the
front drivers side spindle because of the tight
fit.ever since it travels a good inch or 2 when I put
the vehicle in reverse. It shakes the engine and the
sound makes my heart stop. It has been making
the noise for 2 months. Should I just replace the
whole transaxle left driver side front? Also my
vehicle travels back and fourth at high way speed
and greater. I replaced the drivers side tie rod and
gave her a full alignment. It sort of drives like my
old Oldsmobile 88 lol. Really boat like and the
steering wheel can be turned slightly left or right
without Turning the car at highway speed. In a
slight corner in will sort of snap into the curve. Any
ideas on suspension work required? I'm a DIY guy
with minimal mechanical experience . I know what
I work on and that's it. Thank you for future help!

P.S. if y'all have any ideas on making her faster ill
take your advice!