I haven’t messed with a tundra yet but have done the work on an 08 4Runner. It was similar.
If there’s no dipstick chances are it is the same. I bet tons of people have done this to their tundras and documented it online. I’d find a factory service manual to confirm.
I agree with bloc. My Trooper, 4Runner, LX and some other vehicle I have personally serviced* service the basically the same way.I’m changing the fluid and filter on mine within a week. It’s one of the best ways to preserve the life of the transmission.
*I will edit with the vehicle in question when I remember. (Getting old is both beautiful and sucky at the same time.)
I’m a firm believer that servicing is hugely important. If you don’t get all the fluid out because of an imperfect technique your still miles ahead of not servicing the transmission. If you get the fluid level fairly close to correct and leave a quart of old fluid you’re still ahead. Watch some youtube and just do it...