some have 31\2 inch axel tubes the new ends are for 3 inch tubes 3 inch tubes can be put in the 31\2 '' housings but require a lathe and some free time .
I use the 3in ends on my axle tubes was not a problem. That's the nice thing about a welder or having duct tape or bailing wire one way or another you can make it work.
Have even used the ends off of an old 8 3/4 housing on a Dana.