Hi Swifty, Harbor Freight has a relatively new item that may help your situation. Very long pair of needle nose pliers with extra joints allowing them to stay narrow. Length is approx. 16".
Also if you can apply air pressure to gearbox
while vacuming it could greatly increase air flow. I would think the seals
could handle at least 20 lbs. or so.
Also mechanics often put zip lock baggies containing proper amount of gear
oil inside differential covers as an easy way to fill in hard to reach filler conditions. Plastic of ziplock baggies eventually become part of oil,
however auto differentials are beefier than transmissions and I don't know if they use the method in more complex differentials containing clutches etc. [Posi- Trak etc.]
I once dropped a nut bolting torque converter to flywheel into the bellhousing while installing transmission
in my Ford Explorer. [Nightmare project]. Working thru starter hole as that is only way to access these nuts was hours long attempt trying to retrieve nut using wires magnets etc. The problem was the flywheel end ring dear almost totally blocking access into rest of bell housing. I didn't want to remove transmission
to access bell housing as I had returned rented transmission jack, and also removing transmission is horrible project
without automobile lift
I couldn't rest easy knowing the nut could possibly bounce into ring gear and starter gear causing problems. My solution was to drill access hole thru bell housing using 1" hole saw to cut hole near bottom forward of flywheel to access that area. I still couldn't find the nut with much probing around torque converter and flywheel. Mystified, I replaced the starter and ran the engine
which rattled the nut down to the hole area
allowing me to retrieve it. I don't know why Ford has studs on torque converters making it harder to install transmission. Chevy uses bolts making the process much easier. That's my 2 cents worth. I hope some of this will help your situation. Potbellypirate