Changing one of minecraft's block's drops.

[hbh7]

Hello and thanks for checking out my topic. I have another question about modding.

 

So I have been looking on the internet for a way to change one of minecraft's blocks to drop a different item occasionally. I only found ways to do that on a block that you create. I want to make it work like gravel does, usually dropping gravel, and sometimes dropping flint. I just need a way to modify(or way around it) the minecraft block class to do this. (NOT gravel, a different block that is from vanilla minecraft, possibly multiple blocks in the future) Does anyone know a way to do this? Thanks in advance!

[larsgerrits]

Use ASM. That's all i can say.