Should there be a small hle in the bottom of my standard transmision case

The speedometer adapter is probably siezed in the aluminum case. Try working it loose with a can of Wd40 or equivelant, tap gently on it with a hammer to work the lubricant into the speedometer bore. Use a pair of vice grips to rotate and remove after you take the small clamp that is holding the adapter in

To drain the trans there is a 12 mm bolt on left side of case at bottom

To check & fill ---if you face the side cover & look to the left -down on the case- there is a bolt you remove & the dip stick comes out

You fill with GM T-IV Fluid #88900925

I guess that is avail dealer parts only

Depending on what model this but by the side of the gear change lever is often a small cover that looks like a usb plastic cover on a phone ,if so lift this and push the plastic bit at the bottom of the hle andf this will release the gear lock mechanism

ya.. its way easier to remove the sway bar than the transfer case...

The mechanics lied to you. Changing the transmission fluid and screen will not cause any car not to run. Just as you need to periodically change the oil, the same holds true for transmission fluid. Though the fluid is black, yoou state that you have no slippage or nothing out of the ordinary. If that is the case, then you do not need a new transmission. Just have the fluid and screen replaced and all will be fine. Make sure to pick up a transmission pan gasket while you get the necessary fluid and screen. Again, changing the fluid will not cause any car to not run. It is safe to perform the fluid change.

location of the filler being at the back of the transmission.
It is just a small little thing that you cant hardly see or reach. 17 mm one is the fill one. It is just like a bolt on the side of the transmission. You have to pump fluid in.
The reason for this is that VW has a policy, or believes in their oil lasting the lifetime of the car. Most people are finding that this is not the case.

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

left hand side of the motor near the fire wall closest to the windshield look for a yellow handle it will be short and may be in a difficult location to see put just poke your head in there and look...
if this is a standard tranny there will be no way to check othr than opening up the filler hole on your tranny


ps

If your vehicle has the 5.2 liter,aka 318 cubic inch engine,there is only one transmission model applicable and it is the 42 RE which used to be designated the A500.It is a 4speed overdrive transmission.If installing a rebuilt trans and new remanufactured dry torque convertor.You add 4 quarts initially,then fire the engine and add another 5-6 quarts for a total capacity of 9-10 quarts.Fluid level is checked with the trans in Neutral.If you are only dropping the pan,you will replace roughly 4 quarts.The transfer case fills separately,but uses the same automatic transmission fluid.Capacity for the transfer case is about 2 quarts/fill to the bottom of the fill plug hole.Good luck.

there is an oil seal between the transfer case and trasnmission housing, if your bearings have gotten hot in the transfer case, this could have caused the oil to heat up and damage the mechanical seal