Here's how I do it
Take everything apart.
With the empty box on the bench flip it nose down.
Remove the tailhouse from the M/S.
Drop the loaded M/S into the box, and slide a couple of flat bars(*see note 1) between the bearing and the box. Snuggle them up to the M/S as close as you can get them. I actually made a slotted plate just for this. Remove the snap ring.You may wish to install spacers between the sliders (*note 4) and the gears under them to prevent the sliders from falling down and popping the struts out of position.
Place a brass chunk of metal on the M/S and pound away with the biggest hammer you have; at least a 20 ozer. When I say pound, I don't mean as in pounding fence posts; you want to have a bearing left when you're finished. You need the big hammer, so you don't have to concentrate so hard on hitting the target. You need the brass chunk, or any chunk softer than the M/S, yet strong enough to survive the pounding, to save the splines. The bearing is not that tight on there. Don't use any softwood, it will explode and make a splintery mess. A chunk of Hardwood might survive.
To reinstall it; flip the box, front end up.
Cut a hole in your workbench to receive the M/S. Borrow the outter snapring from the front bearing, and install it onto the rear bearing, and drop it into the front hole, correctly oriented.(*note2))
Drop the M/S thru the correctly oriented bearing,WITH low gear on it, and into the box tail-first, dropping the shaft down thru the hole in the bench.Verify the bearing is correctly oriented,lol. Then;
Back to brass chunk and hammer; except now you have to steer the assembly straight down checking after every whack, and adjusting the next whack.Plus you have to steer the m/s into the low-gear bore.(*note6) Finally re-install the rear snapring and return the borrowed outter ring.
NOTES
(*1) these flat bars need to be as thick as possible so they don't bend, yet thin enough so you snuggle them up to the m/s to support the inner race. I don't recall how thick the plate is that I fabbed up, and I know there is not much room in there. I'm gonna guess that 3/16 is about the max that you can fit in there. Use whatever you can. to get the bearing moving, and then reposition the bars after every whack until the bars are up tight to the m/s. Whatever soft chunk you use to protect the m/s,will absorb some of the shock of the the hammer blows.
(*2) Instead of this method, you can install those flat bars you earlier used. You just move the box to the side (we're not gonna use it), and place the bars between the bearing and the steel workbench (*note 3), again snuggling them up close to the m/s.Then the slider supports, and then the brass and hammer again.
(*3) No steel table? then bring the box back and put the flat bars between the bearing and the box.The rest is the same.
(*4) the slider supports only need to be thick enough to prevent the sliders from falling all the way down onto the gears under it. When this happens the struts usually pop out the backside. If this happens to you,don't panic! They are easily re-positioned with a small screwdriver, and a little upwards pressure on the slider until the last one pops back in. Then the slider will pop up into neutral. But you do have to be careful to make sure that the energizer spring gets properly captured by each strut. No big deal.
(*5) Some might think that all that whacking might damage the races. Well firstly you'd have to be brutal. And secondly even if you managed to drive the balls into the races, the divots would be on the sides of the races. This is how I was taught to do it when I worked in a tranny shop. In 5.5 years, I never had to warranty a bearing. Heck I don't recall any warranties of any kind ever. And I have put around 300,000 miles on a total of 3 of my own transmissions built this way,since 1972, with no complaints.Your results may vary.
(*6) sccachallenger mentioned using a pipe; this works too. The set-up is a little different. Just ask if you can't figure it out.Using this method the low-gear stays on the m/s by gravity, and all the force of pounding goes straight into the inner race, and from there into the soft steel table, and little to no steering is required to slide the bearing into place. And you can pound directly on the end of the pipe,but if you do,the pounded end of the pipe is usually sacrificed, so it's a one-time use tool.
