I went ahead and built poly bushings for my front differential. I focused on building the notorious upper mount that, once you replace it, you never want to do it again. I wanted to use poly for its longevity but did not want the extra NVH so I used softer poly for that. I designed the bushing to be a bit more beefy and seem to have struck a happy balance between performance and comfort. Here are few pictures. I am also listing the extra few pieces I built on ebay if anyone is interested. Thanks for checking.