ORIGINAL: Max 86
Here is my formula for division level games. The intent is to have all the major elements of a division in suitable numbers to best reflect partial casualties in a particular combat without losing all of the division's capabilities. Also, I have put aside the one for one comparison and have tried different multipliers for different unit types.
Inf Btns: multiply # of Btns by 10 (Inf Div with 3 INf Reg/6 yields 60 infantry. Out of that 60, 40 Rfl, 10 SMG, last 10 between mtrs, bazookas, IGs and MGs, player discretion according to mission.)
Eng Bn X 10 also. So one Eng Btn in the division = 10 Engs
Divisions usually had Rcn, Arty, AT, Flak Btns. For these battalions multiply by 2 or 3 ( I haven't decided yet). So each division with a Rcn Btn will have 2-3 Scouts or Scout Cars. Same for the other elements.
Transportation I try to keep simple; Mechanized Divs have halftrack/truck mix, Motorized Divs have trucks only and non-motor/mech (groundpounders) use 3:1 horses to truck ratio. Unless the scenario calls for a lack of transport, supply enough of the correct transport for the entire division.
Tanks represent a different animal entirely, initially I thouught 1 tank per tank company in the division but that would lead to as many as 16 tank units for a 2-Tank-Regiment division which is way overpowered for this game. So, try using one tank per tank type per regiment. Confused yet?
An early '42 German Pzr div might consist of 1 Pzr regiment with a PzII company, 2 PZIII companies and a PzIV company (Based on the Campaign Series model for sake of discussion). This means that this division would receive 1 Lt tank and 3 Med Tanks with the PZIV classified as a medium. I am planning to allow both Med Tk 1 and Med Tk 2 to be produced simultaneously (if possible) to represent the PZIII and PZIV medium classes.
A 2-regiment tank division based on the model above would have 2 Lt tanks and 6 mediums.
To summarize;
Inf Div with 3 Inf regiments and Rcn, Arty, AT, Flak Btns would consist of:
40 Rfl, 10 SMG, 3Mtr, 3MGs, 2IGs, 2 Bazookas
10 Engs
2-3 Arty
2-3 Scouts
2-3 AT guns
2-3 Flaks
Tank Div with 2 Tk Regiments and Rcn, Arty, AT, Flak Btns would consist of:
2 Light tanks and 6 Medium tanks
10 Engs
2-3 Arty
2-3 Scouts
2-3 AT guns
2-3 Flaks
Again, the idea is to be able to send these divisions into combat and sustain a few losses without necessarily losing divisional capabilities like Rcn, Arty and so forth; but prolonged combat will still grind them up into a shell of their former selves.
The Hv tank Btns is another situation completely because the heavy tanks are so powerful in this game. I use 2 Heavys, 1 light and a 2 scout cars. Only 5 units but they pack quite a punch and if losses do occur, it will not necessarily be the heavys that are lost. I may remove the scouts and add light tanks because I am not sure if these Hvy Btns carried a scout company or not. Must research!
This is not set in stone but just a template to go by. Still use historical data to flesh them out. For example, I don't think Russian tank divisions had any mobile arty so do not inclued Arty in the Soviet tank divisions. Some divisions did not have Rcn cars so use foot scouts instead. stuff like that.
I know this must be a great game because I have started a notebook for keeping track of things! [:D]
Max, this is great...a really good starting point to nailing this stuff down. I would also agree with the other poster that you should add infantry to the Tank divisions...I'm pretty sure German WWII tank divisions had 1 or 2 infantry regiments in there. Thanks for the work Max, I'm going to use this!
i never got around to making this sort of scenarios though. 
