Mine rattles a little bit. but I had another rattle problem before.
I was sure it was the transmission. but it ended up being my idler pulley. it would rattle in neutral and idle speed. after changing the idler pulley the rattle went away.
You might want to check it. it was a 20.00 fix.
"Let me not pray to be sheltered from dangers, but to be fearless when facing them."
1999 X-star, 330 LTR, Zero FLex tower.