Driver side axle won't go in!

Fresh rebuild for an 8 3/4 rear in a 70 B Body. Driver side axle bottoms out about 1/4 inch out. Never had problems with this in the past so am looking for any thoughts as to what it might be before I pull the punkin back out. Does it regardless if the passenger side is in or not.
Any help is appreciated.
Thanks in advance!

If you have a clutch type differential , there is a centering button that can fall out of place in the center of the differential and cause your problem.

sometimes you can use a long magnet and put it back in position. Worse case, you must pull the center section, reposition it and reassmeble.

Pull the axle and take a look at it.

Another possibility if it a OE locking diff of either design the splines between the side gears & the locker may be mis-aligned... Try locking the passenger side axle, bolt a wheel but no brake drum to the drivers side axle, grab the wheel & rock it back & forth while pushing in... Often the splines will shift slightly & the axle will slide in...

If you changed from the stock caged bearings and adjuster to the "green" bearings, you may have to remove the centering button from the differential.

Thanks for the replys! I had done the alignment thing you describe previously and it allowed it to go in from about 3/4 of an inch to the current 1/4. Can't really tell but the button appears to be ok as we'll. Going to take some measurements to try to verify. Btw it is a factory diff no green bearings.
Thanks again!

Did you try backing the adjuster off on the passenger axle?

Back off the adjuster, that's the answer.

Got it!!! After measuring both sides i found the button locked to the left. Apparently it cocked just enough that when I pushed the axle in it wedged it tight. I was able to take a broom handle and tap around on it and it finally get it freed up. Both axles slipped right in and adjusted out fine. Thanks to everyone for their advise!

Good job.

Now show us some burn out pics

codfish

Thanks, will do!

One last question. Did you hand pack the axle bearings. They are not lubricated by the rear end lube.