This from John Gill's 1809 Thunder on the Danube (Volume II p366 & notes on p437):
Advance Guard: GB Desaix
1st Combined Voltigeur Regiment (Col. Nagle) 3 battalions
2nd Combined Voltiguer Regiment (Maj. Vautre) 3 battalions
Strengths of the voltiguer battalions (eight companies each) estimated at 700 to 800 each battalion, giving Desaix an infantry strength of approximately 4,800, though it may have been as high as 6,000.
Composition of Combined Regiments – contributing regiments – as follows:
1st Regiment: 1st Battalion – 9th, 11th, 84th, 92nd Ligne
1st Regiment: 2nd Battalion – 18th Leger, 13th, 23rd, 29th Ligne
1st Regiment: 3rd Battalion – 35th, 53rd, 79th, 106th Ligne
2nd Regiment: 1st Battalion – 8th Leger, 1st , 52nd, 102nd Ligne
2nd Regiment: 2nd Battalion – 22nd Leger, 23rd Leger, 60th, 62nd Ligne
2nd Regiment: 3rd Battalion – 112th Ligne, 1st, 2nd, 3rd Italian Line