i like using them on the 40s because of the increased bushing diameter. especially on the stock front springs, the bushings are soooo thin that you'll destroy them in one trail run. the center pin is in a different location so you'll either have to leave it alone and modify your wheel base or re-drill the top spring. the rears on the 45s hold up pretty well.
conversion bushing s are avaiable from sor. i try to keep them in stock at all times.