See my posts in "Russians in 1805 Campaign" Topic at TMP link
In additionL from page 95 in "1805 – Tsar Alexander's First War with Napoleon
The Russian Official History"
Alexander Ivanovich Mikhailovsky-Danilevsky
Translated by Peter G.A. Phillips:
Reserves
Tsarevich's
Units;
Chevalier Guard Regiment.
Lifeguard Horse Regiment.
Lifeguard Hussars.
Lifeguard Cossacks.
Preobrazhensky Regiment.
Semyenovsky Regiment.
Izmailovsky Regiment.
Lifeguard Jäger Battalion.
Leib Grenadier Regiment.
Lifeguard Artillery Regiment.
Nafziger shows at Austerltz the Russian Guard as follows:
Reserve: Imperial Russian Guard: Grand Duke Constantine
Brigade: Generallieutenant Kollowrizov (6,500 inf)*
Guard Jager Battalion (300)
Semenovsky Guard Regiment (2)(l400)
Preobragensky Guard Regiment (2)(l500)
Ismailovsky Guard Regiment (2)(l000)
Leib Grenadier Regiment (3)(2300)
Guard Pioneer Company (l00)
Brigade: Generalmajor Jancowitz (2,500 cav)*
Guard Hussar Regiment (5)(800)
Chevalier Guard Regiment (5)(800)
Horse Guard Regiment (5)(l000)
Guard Artillery:
Russian Guard Artillery Battery (8 6pdrs)
Russian Horse Artillery Battery (8 6pdrs)
2 Russian Light Batteries (l2 6pdrs each)
The basic OB comes from an Austrian source. Those portions marked with an asterik come from:
S'ornik' Istoricheskikh Materialob' Izvpechenn'kh iz' Arkhiva
St. Petersburg, l902