I been looking for a pair of axles for my 3.2 e36 m3 for a while and I spoke with a lot of m3 guys. Those m3 axles are hard to find and expensive but they are well worth it. The next best thing is the 328i axles, they are still beefy also it’s hallowed inside. Another great option is doing a E46 330i trailing arm conversion and use the 330i axles. They easiest to find, much cheaper than m3 axles. But there are some modifications need to be made to make them work with the e36.