Transmissions don't usually have a drain plug. You have to pull the pan and replace the filter while the pan is down. Always replace the gasket when you pull the pan.
about 2 grand for automatic trany if you can find one
Its on the side of the transmission right next to the oxygen sensor on the driver side near the front of the car
If it is automatic, you should be putting the manufacturer recommended ATF (automatic transmission fluid) into it, NOT gear oil. There will be a plug on the bottom somewhere to drain it, and you will likely fill it from the dipstick tube in the engine compartment. Check your owners manual, or find it online, or call and ask a dealer about what you should be putting in the transmission and where.
where can i find the transmission drain plug for the Mazda
It is on the bottom side of the oil pan. If you cannot find it, then you are not qualified to change your own oil.
straight down the dipstick hole. (the dipstick you removed to check the fluid level)
You can buy a manual on line fot the specific automobile you have that has all the answers to servicing that certain make and model. My husband just boutgh one for his auto to find out how to drain and refill the transmission fluid.
The transmission oil drain plug on a BMW 3 series is an Allen plug, usually 17mm, on the bottom of the transmission.
If the vehicle is an automatic transmission then you will find a DIPSTICK inserted in a filler tube that goes down to the transmission . Locate the tranny in the engine bay and you will find it. It IS IN THE ENGINE COMPARTMENT and is very similar to the OIL dipstick but it IS LONGER. If the vehicle has a MANUAL (w/clutch) tranny then the only way to check it is from underneath the vehicle by unscrewing a drain or drain/fill plug. This is always on the SIDE of the transmission and looks like a HEX bolt.
There is no transmission dipstick on automatic or manual transmission Passats. The automatic (tiptronic) transmissions have a "lifetime" fluid that can generally only be changed by the dealer.
on automatic transmission
I cannot find the transmission lipstick on my 1998 F-150 with a manual transmission.