[54Rich]

I have a used trans, was told it was stock from an unbeat car and a rebuilt D5, the trans shifts nice everything is as good as it can be right now. However, in OD starts around 45 to about 55, the trans feels like it's pulsing? At 65 it's fine and if I take it out of OD it's fine. Any idea what the problem is? As far as I know this trans is stock.

Thanks