PzJgAbt “GD” was ordered to disband on 27 February 1944. Shortly afterwards it was incorporated into various companies of the division and ceased to exist.
On 13 December 1944 the Abteilung was created again. It consisted of Stab, StbKp, two (1.,2.) JgPzKp (PzIV/70), (3.) PzJgKp (mot Z) and VersKp (mot). 1., 2. and 3.Kp were created respectively from renamed 3./PzJgAbt "Br" of PzGD "Brandenburg", 4.(PzJg)/PzAbt 2104 of PzBr 104 and 15.(PzJg)/PzGR ''GD".
On 10 January 1945 it was reported that PzJgAbt "GD" (except 3.Kp which remained with the division) had arrived at the Mielau training ground. On 12 January 70% of its personnel were available (the rest were on the way). On the same day its 21 PzIV/70 arrived too.
On 16 January PzJgAbt "GD" (with 21 PzIV/70) was shipped from Mlawa (Mielau) to the front to join its parent division. However, during the same day it was attacked by the enemy in the vicinity of Ciechanow (Zichenau) (southeast of Mlawa) and wiped out. Its remnants retreated to the north towards Allenstein.
On 9 February an order was issued to recreate the decimated PzJgAbt "GD". The rebuilding was to be carried out at the Grafenwöhr training ground. On the same day it was reported that the personnel intended for the recreation of the Abteilung is ready for transfer to Grafenwöhr. Moreover, 40 men were provided by 7.PzD. 3.Kp and the elements of Stab remained in East Prussia. They were consolidated into a provisional PzJgAbt that consisted of Stab, StbKp, one (3.) PzJgKp (mot Z) and two FlaKp (mot Z) equipped with 2-cm Flak (mot Z).
On 25 March it was reported that PzJgAbt "GD", which was stationed at the Grafenwöhr training ground, was 100% replenished with personnel, but still has no heavy weapons (The majority of the men were drafted from WK XII). The Abteilung never joined back its parent division. On 4 April it was ordered to assign to the newly formed PzD "Clausewitz" and shortly afterwards was equipped with StuG III and sent to the Western Front. During the same month it was wiped out in the vicinity of Uelzen (southeast of Hamburg).
Hope this helps.