I had done a lot of research when starting my German Long Campaign a little while back. Core force was built as a Kampfgruppe of 1. Panzer Division, including a Panzer battalion inside it. Here is September 1939 OOB for 1. Pz Div. / Pz. Reg. 1 / Panzer Abteilung I, according to historically available tank numbers for that division:
https://docs.google.com/spreadsheets...it?usp=sharing
Other battalions from other divisions will have a similar structure with changing availability of Pz I, II, III and IVs and sometimes Pz-35(t) and Pz-38(t) thrown in.
There are also Panzer Signal Platoon, Motorcycle Messenger Platoon, Reserve Tank Detachment, Light Panzer Transport Column and Tank Maintenance Company but I did not include them to preserve core slots for the rest of the Kampfgruppe (Inf, Artillery, AA etc).