Some months back there was a thread on clunking hitches.
I've had the same hitch and draw bar for 7 years and never had a problem.
I towed my 82 13" Scamp
down to be measured up for a new axle
Every time I hit a small bump in the road it sounded like my hitch was falling apart.
When I towed it home when I bought it there were no clunks.
The noise was caused by NOT ENOUGH tongue weight
There is a heavy duty extended rear bumper that adds about 70 or 80 pounds to the back of the trailer.
tank and battery
were removed taking a good deal of weight
off the tongue.
If you have an clunking hitch check you tongue weight