Unfortuanltey those bushings are not replaceable and theres nowhere you can find them. You can however swing by a junkyard and look around at some explorers because a lot of them had a tranny crossmember that mounted solid to the outside of one frame rail and then solid to the lower rail of the other frame rail. From what I have seen of them the frame should have all the holes needed to mount this crossmember, or at least the 93 and 94 ranger frames do, but I wouldn't be surprised if the older ones did also, if not it may be just a matter of drilling a hole or two. One side of the explorer solid crossmember mounts using the 3 holes that should have rivets in them on your B2 in a triangle pattern holding the mount to the frame.
