Triumph Repair: Steering / Alignment, tie rod ends, nissan altima

Question
I get a "thud" when I turn the steering wheel a bit, and might "thud" again as I keep on turning the steering wheel.  When I turn it the other way, the same thing happens.  This happens with the engine off or on, while it's parked or  driving down the road.  Sometimes, the wheels will be aligned when driving down the road, then after a "thud", the car will pull to one side.  But after another "thud" when turning the steering wheel in the opposite direction, the wheels can be aligned again.
Other info:  Front wheel drive
Nissan Altima, 1996 GXE

Help would be appreciated!

Answer
Andy,  they put your question in the wrong area as i'm a Triumph mehcanic. I will make a guess that something is wrong with the steering rack or the tie rod ends which connect the rack to the wheels. you might look under and see something loose , sorry for not being much help. Dave