I use the following
a counter-sheet scan from a board wargame- "Red Badge of Courage" (open image in new window/tab or save to desktop for a better look):
The designer got his information from the O.R. and other first person sources, so the history is solid. The actual regiments and batteries have icons of infantry, cavalry, and artillery, the numbers along the bottom of each unit being, from left to right: strength points– morale rating (on a scale of 0-9) – and movement rate. Each strength point equals 50 actual men or one artillery peace.
Regiments are usually divide into "wings," parts a and b. Sooo for example, the two halves of the 33rd VA have 9 strength points totaling 450 men.
The units making up a brigade are color-coded, so you'll have to match them up to their leaders. Also, units in the area but that did not actually fight-- such as Richardson's Union brigade, a Union division under Miles, and unbrigaded regiments under Runyon-- are not shown. I actually found the OOB's for those "spare" units from, of all things, a computer game called Take Command: Second Manassas.
Oh and, a M or R in within the flag of the unit means a primary weapon of Smoothbore Musket or Rifled Musket (AR or ER stands for Enfield Rifle or Austrian Rifle, if that matters). The abbreviation of weapon type for each battery I can provide later if needed.