I feel confident it is and AOD if it is an 89 truck...the AODE was not available until 92. The 4R70W was not widely used until 94.
If the TV cable was unhooked, that doesn't mean reverse would not work.
Reverse is stand alone and is not associated with the FWD drum, so there for it is very common that it will be left working - until you use it enough to kill it too
