A833 assembly tricks

haven't done that (cover is still on the bench) - now how to do that properly?
Just put the cover in any gear, then try the OTHER lever and see if you can get a second gear.... Which you should not be able to.
In the late style cover with the scissor interlocks, you have to install the forks and then it is impossible to get two gears simultaneously.
But the early covers will get two gears if the interlock lock-out pin goes missing.
With either cover, after it is on, and with at least two of the big-shoulder bolts installed, push the cover "up" as far as it will go, tighten them, then make sure that reverse can still be easily selected.
Make sure the oil baffle is installed in the tail under the vent .....
Did you replace the O-ring on the reverse shifter shaft? You have to remove the reverse idler gear to get that thing outta there. That can be a PITA, so that O-ring may get overlooked during several reconditions and eventually it leaks. Sorta like the back-up light switch which leaks right thru the bakelite seal on the contact spades.
Good on you for doing all the other tricks.

I actually remembered your technique before I started but the cluster pin didn't clear and since I had everything painted.....
That is so cool
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The method you used looks like a reasonable alternative.
However, there is a third method that I have used.
It goes like this;
FOUR decades ago, I was employed by an up and coming driveline rebuilding shop. I started out doing Pass car/light truck 3 and 4 speeds from the early 80s and older.
They gave me a steel workbench with a rotator on one end (like an engine stand) for doing rear-ends. I could bolt the loaded case on there horizontally; then walk the tail right in the backdoor; Badaboom! That is how I was taught.
But I stopped doing it that way when I found out that I was strong enough to just drop the tails down. Not bolting the transmissions down and dropping the tails in from the top, allowed my weekly productivity to jump considerably which pleased the boss enough to give me a nice raise....... which was nice cuz the babies had started arriving about every second year.
The boss was pretty in tune with his business, and as soon as he discovered my talent (which I didn't even know I had), he rapidly moved me into more complex, and lucrative for him, builds. And when he found out I didn't have to take stuff apart in order to put it back together, but could work of drawings, well that chit got real. Now I was being paid the big bucks!
By 1980, there wasn't much I hadn't built, but since my favorite builds were RoadRanger transmissions, those were the bulk of what I did. By 1981, those were no longer on the plate; as now, I was doing power-shift transmissions for mining equipment, and for hiway equipment, that were so big that I could nearly stand up inside them.
I worked there for 5 and a half years and during that time, I watched that business double in size nearly every second year. But, I decided to leave the big city, to raise my kids. I heard they hired three new guys to replace me, when I quit, so maybe I really did have a talent, lol. That was a great job, and the guys were great. I missed it for a long while after I quit.