OT kind of but, relates to trucks too
 

My son hit black-ice and put his 03 Mustang GT and met a curb. Ordered two axle shafts from summit with bearings and seals. While installing shaft It did not want to go through bearing without being tapped with mallet. I was sure I heard bearing seat into housing but..... Can new axle and shaft be that tight going into new bearing.

If I understanding what you're doing, my experience with older vehicles was the bearing had to be pressed on and off of the axle.

I'm thinking you are correct.

Yup, I'm pretty sure that it has to be pressed on.

However, sometimes you can cheat
I've gotten lucky a few times with a hammer and punch and slowly working around the inner bearing race. Usually in a criss-cross pattern. Sometimes you can convince the bearing to work its way on the axle shaft. The key is to go slow and steady and not try and force it all the way at one time.

That being said, if you have a NAPA or other machine shop close by its easier to just have them pressed on the proper way.
Bobby

You should have 8.8 rearend with c-clip axles, so the bearing is not pressed on, axle should be free to slid in bearing. I would measure bearing diamater on old axle and compare to new axle. Is it possible the housing is bent? The axle is the inner bearing race so I wouldnt want have it to be too tight.

I remember my dad, who was a mechanic with his own shop, installing an axle bearing on his own car using a large piece of pipe and sliding it up and down, like driving a fence post. He would never do this with a customers' car but with his own car he would never dream of spending the $1 it probably cost back then. Now it probably would cost maybe $10-15? We worth the aggravation and making sure it's done correctly.

Ditto as last chance stated. Did you try the bearing over the axle before installing the bearing in the housing? If you have the bearings already installed in the housings, you could go to a parts place and get a new axle bearing and try it on the axle.
That bearing fits a lot of years (1967-2011)

The 8.8 axle is c-clip. I don't think I distorted the bearing when installing it but I'm not sure. I'm gonna check while I have light today........I just checked other bearing and shaft and bearing slides on fine. Looks like I'm pulling the shaft back out inspecting and getting another bearing. :(

Was the bearing still in the axle housing? If so it is possible the housing may be bent and/or the bearing damaged. Did the original axle slide out without force?

If the 8.8 is like a GM C clip style with the bearing in the end of the axle tube then the axle should slide in easily. I agree that the axle tube could be bent, especially if he bent the original axle.

Even on a C-clip axle, "some" force is needed. The axle shaft shouldn't spin freely in the inner bearing race. "Tapping" is fine, but if you needed to whack it, that could either mean it was cocked a little or there was junk on the shaft.

On an 8.8 ford the axle should slide freely in bearing, The axle surface is the inner bearing race. I do not know about gm axles I try to avoid them!!!

GM 10 bolt and 12 bolt C clip rears are the same way. Now you know something you didnt want to and are forever scarred :)

It was a joke, Was trying to stir the pot a little, I had the misfortune of working in a gm dealership for awhile so I knew that. Now please do not think less of me for having worked there!!!! I also WORKED AT A FORD dealership to make up for it!!!

You're right, I am used to 9" axles and the D44's. Running rollers right on the axle can't be a good idea.