when you say check bolt i take it you are referring you the filler bolt you remove to check the level of the tranny. because you should feel fluid on the bottom tip of your finger when you reach in the filler bolt.
you can't check the fluid of the tranny from the drain bolt (the one you put the rachet directly on) since the fluid drains from the drain bolt.
so now i've heard of people removing the filler bolt, AND the speed sensor to fill the tranny fluid through the speed sensor and let it pour out of the filler bolt. that makes absolutely no sense to me.
i mean seriously. i've used a funnel with a tube for years. not issues at all.
frankly i've seen 2 speed sensors break when removed.
i advice you use the filler bolt to fill the tranny.
also have the car level will filling the tranny, if the front's jacked up, fluid comes out of the tranny before it's actually full.
it's also not a bad idea to replace the washer on the drain bolt when you do it.