help needed with 904

Well in typical shape our fashion we may have a whole switch around right in the middle of everything! There was grey matter all over the other transmission filter but apparently the filter was working well because it kept it out of the transmission. I'm pulling this Heather transmission apart and it's looking extremely clean inside the drums aren't all burnt the band look great and everything looks very stock and the transmission is literally 10 years newer. It definitely looks as if it's been rebuilt inside just by exterior appearances of the interior. Oh boy

Yep, you might just do that one instead then.
Grey and/or black goo is usually aluminum that wore off of something, like the inside of a converter.(the fluid pressures wear the aluminum off vanes and such inside converters)
Black chunks are burned clutches or bands, silver bits can be disintegrating bushings or needle bearings and silver slivers means hogged out bushings.
(Just general info):D