this is not a fresh trans build,i built it roughly 4 yrs ago but only has maybe 350 to 400 miles.the trans has always shifted fine and reverse worked as normal.drove to work other day everything was fine.went to back the truck up in driveway other day and reverse acted funny.all forward gears shift as it always has.i looked at the rear servo with a flash light and didnt see any damage.i did not not remove the servo too look at it.applied air pressure to l/r servo and it applied and released.held the air pressure to it and did not hear any leakage.while i was there i re-adjusted the l/r band also.the valve body was removed while doing all this.