I guess you're asking whether any Independant Rail locomotives have been created for MSTS.
I'm not aware of any such models in IRA colours. The Danish MZ loco has been modelled overseas, as shown here;
http://msts.banal.net/catalog/pages/Denmark-Diesel.html
The loco in its Danish form is different from its current Australian form. The buffers, 'snow plough' as well as other external detail were removed when they came here, so anyone wanting to reskin an already-existing MZ would need to take this into account.
IRA's 4497, recently repainted into silver, is a possibility for reskinning an existing 44 class loco.
Cheers,
Matt