Elektor Formant Modular

hi. i just fried my 7413's in the two vco's.(wrong polarity)
are there any ic's that can replace this?
can you still get the 7413?
thanks  alot!

By the way. i bought this:SN7413N
Is that the same as the original 7413? i replaced them with the 
original 7413's but there was still no sound. So the question is: is 
the new IC not the same as the old one?  ( or maybe the 7413 wasnt the 
only thing i fried.)
thanks!