From "Germany's Lightning War" by Adrian Gilbert (2000), page 189 he states, "Its small peacetime army of 150,000 men could be mobilised to approximately 1.4 million troops..." And he describes the Germans as meeting almost no resistance. He lists about 343,000 men as captured and 300,000 as slipping away (nucleus for the resistance). German casualties were 392 wounded, 15 missing and 151 KIA - obviously not a hard fought battle
Yes, those figueres are much closer to what I have.
The peace strength of the Yugoslav army today is 150,000 soldiers, 8,200 officers and 9,400 non-commissioned officers. Its armament comprises 2,000 light machine-guns, 800 heavy machine-guns, 250 batteries of artilery, five tank companies, and 45 air squadrons. A general field mobilisation would place at the dsiposition of its commanndant (active and reserve), 1,200,000 first line combatants thoroughly trained and admirably organised, and about 400,000 territorials, more than half of whom are war veterans. Such an army is terribly expensive.
Out of a total of 1,040 million Swiss francs, the Yugoslav budget for 1932 allotted 277 million, or about 27 per cent, to the Ministry of War.
Now, an peacetime army of 170 000 men is by no means small, but rather a very big army. I will fetch the numbers of other Balkan peace time armies (I have to look trough a militarty encilopedia

) but from my memory, only Turkey had a larger army then Yugoslavia.
Also, when Greece could field 460 000 men with a population of 7 milions it isn't unreasonable to belive Yugoslavia could field twice that, with a population of 15 milions (and one of the fastest growing population in Europe).
Historicly, there was no war between Germany and Yugoslavia, basicly the serbian Generalstaff was convinced they had no chance and acted the same way. Also, the army was mobilizing, while Germany was prepared for the attack on SU, this two things combined were the prime reasons for the fast conquest of Yugoslavia. (In game terms, the yugoslavian player reinforced all his divisions to full strenght, and suffered org close to 0 for it, the German player used that to full extent

)