Brown fluid - very bad sign. Depending on how often the fluid was changed you could cause the tranny to fail by changing the fluid. I have it from several dependable sources that if the tranny has not had regular fluid changes, when you put fresh fluid in, they often fail within a few months of the change.
The B2 piston is not used for reverse at all.
Its my guess that you are in for a rebuild soon.
I got too many cars!! Insurance eats me alive. Dave
78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k