Transmission Problem

[sadamz_boss]

I Have a 2008 GMC Sierra 2500 HD when i shift from park to reverse it makes this sound it not a rattling like inside the gear no but as if the gear isnt in its place and every time i shift from park it slaps on and i can make the same sound by stepping on the breaks and then gas it also makes this slapping on sound

 

 

 

Thanks in Advance Everybody

[Prokopchuk_9]

How's fluid level?

[gmtech4]

my crystal ball is broken, can you upload audio of the problem,,guessing is ,,,,,,dumb,i want to hear it ....

 

or if oil is silver like ,tranny is done ,,,,4l80 ? ,not sure if you have one or not ,,,2500hd could be a dirtymax and allison

[sadamz_boss]

Fluids are ok i'm guessing that its some sort of housing or bracket or something that rhymes with these words