best thing to do is go to the chapter approved site and download the free PDF files for the armoured company codex and armoured company vehicles list. depending on where you play it is hated or welcomed to have an armoured company. in the area i play it is chapter approved from games workshop so it is allowed. it is banned in some places.
CODEX (scroll to bottom of article)
http://uk.games-workshop.com/chapterapproved/ac%2Darmylist/1/
Vehicles you're allowed to use
http://uk.games-workshop.com/chapterapproved/ac%2Dvehicles/1/
The Source!!
http://uk.games-workshop.com/chapterapproved/
restrictions apply like other codexes with a small difference. for the first two "troop" tanks you need 1 HQ slot taken up. that's ok since the minimum is 1 HQ and 2 Troops for every army. for every 2 additional troops you have to have a "tank ace" whihc takes up an elite slot. most different thing about it. well besides that fact it's all vehicles.. you can have some guys on foot but they have to have a chimera.
CODEX (scroll to bottom of article)
http://uk.games-workshop.com/chapterapproved/ac%2Darmylist/1/
Vehicles you're allowed to use
http://uk.games-workshop.com/chapterapproved/ac%2Dvehicles/1/
The Source!!
http://uk.games-workshop.com/chapterapproved/
restrictions apply like other codexes with a small difference. for the first two "troop" tanks you need 1 HQ slot taken up. that's ok since the minimum is 1 HQ and 2 Troops for every army. for every 2 additional troops you have to have a "tank ace" whihc takes up an elite slot. most different thing about it. well besides that fact it's all vehicles.. you can have some guys on foot but they have to have a chimera.