Bulgarian question: крака

In the book I am reading, I noticed that there is the expression “се изправи на крака”, in which the word крака has the stress on the second syllable, but there is also the phrase “подпрял се на четири крака” where крака has the stress on the first syllable.

Am I right in thinking that the version with the stress on the first syllable is the normal plural count form, and the version with the stress on the second syllable is the singular definite object form, so the expression “се изправи на крака” literally translates as “he rose to the foot” rather than “he rose to (his) feet” as would be the normal expression in English?

It seems that the first example is the ordinary plural, but rather than the expected кракове it is an exception. The second example is the expected “count plural” (or ordinal) form. I hope that makes sense.

btw what book?