727 leaks if not driven

The converter drain back is quite common when sitting for any length of time...
One if the most over looked leaks on a 727 is the rear band pin Oring.
This Oring is at the rear of the transmission ABOVE the trans pan rail consequently is seeps down to the pan gasket area and it usually gets diagnosed as a pan gasket leak.
Its not a simple fix ... it can be complicated if your unfamiliar with automatics. It requires extension housing,pan and usually valvebody just to push the pin out enough to replace the Oring. Probably best left to your local transmission shop.