Question: what version of jdk is bcel 5.1 expected to be run with?

I have been using this tool to create a byte-code enhancement of created 
class files and I kept getting a NoSuchMethodError.

The reason that I get this is because I am running my application with 
jdk 1.3 and the method that causes this exception is the 
StringBuffer.append(StringBuffer) method.

This method does not exist within jdk 1.3 but it is part of the 
distribution of jdk 1.4.

The interesting thing about this is that I was able to build the bcel 
5.1 source using jdk 1.3!

That is why I am wondering which jdk is bcel 5.1 suppose to work with.

thanks,

--Claudio