Your dad's unit, the 289th Infantry Regiment, was one of three IRs (289th, 290th, 291st) in the 75th Infantry Division.
Please refer to my post #868, dated 3-18-2000, for a brief combat narrative for the division.
You may also try under SEARCH:
75th Infantry Division Association,
which should provide you with a host of opportunities, including an expanded combat narrative.
The division entered the line 23 Dec 44, and was engaged for 94 days, during which time it lost 817 killed, 3,314 wounded and 111 died from wounds. That is a loss of about a third of the division strength.
I hope that this information helps you in your quest.
Feel free to contact me if I may be of furtherservice.