Eli Duttman is right, this is an Am radio. Laki101 is from Serbia, and I am also from one of the ex-yu countries. His radio is probably an old Ei.
These used a LO + mixer (ECH8x), IF (EF80 or 89), detector+agc+first AF stage (EABC80), audio output (EL84) scheme. EF89 was used if AGC was implemented, EF80 if not. IF is 455kHz usually. Many thousands of these were made by the 4 manufacturers in Yugoslavia then, with minor variations. FM versions used an extra front end with ECC85, and usually an EBF89 for extra diodes so an FM demodulator could be implemented.
Regarding the original question:
The radio already contains an audio amp, made out of the EABC80 and EL84, and it is of course MONO. If it's a working radio in a good cosmetic state, it's well worth preserving it as such. If not, many such radios have been scavenged for parts, usually the output stages are preserved together with the power supply, the rest is gutted out leaving lots of spare space on the chasis. Stereo tube radios were VERY rare in ex-yu, mostly made by Philips or some of the major German companies, but these were very expensive being seriously hampered by incredible customs and tax duties on imports, and therefore considered high-end.