Gary is right, That's the way they're mounted, at least in the T-72A (T-72M1), and it is a pain in the a** to align them properly, and I'm talking about ALL T-72 kits, even the Tamiya offering. Here you have a couple of pics taken from the now-extinct Tanxheaven.


And one more:

The some grenades have locating tabs, maybe you have to make them a little longer, then file some places to get the correct angle and you have to make a lot of dry fitting to get them aligned properly, a hard work, but It can be done. Just in case you really want a very different kind of smoke grenade arrangement, you have to modify the turret from T-72M1 to T-72B standart (so-called T-72M2):


You'll have to add front armour to the turret and anti-radiation cladding on the roof. This other version is easier to make:
http://www.otvaga2004.narod.ru/xlopotov_8/tank_t72s_01.htmIt is a T-72S. You'll only need to change the front mudguards, scratchbuild a new stowage box for the left side and place the wading tube on the rear stowage box, and a lot of tiny ERA bricks. I think it will be nice to build one of these. Good luck with your project. Best regards.
José.