727 is acting weird

Gentlemen,
Yesterday my trans (727/360 in a '67 Satellite) was acting really weird. With car warmed up, I would shift into D and nothing would happen. Rev up, nothing. Pull it over to 2 and 1, nothing. Put it back in park, back to D, went in gear fine. Linkage is intact, the gear indicator is matched up to correct gear locations. It did this several times yesteday. It would always work on the 2nd try. I checked the fluid, it may be a tiny bit overfilled (my rear end is higher so it is hard to get the trans level without jacking front end, so there is a bit of guesswork), but is good. I'm using type F as recommended by Pat Blais. Shifts great when driving. This morning, when driving to work I didn't have any issues. Heat related perhaps?
Any ideas?

How fresh is the trans? Some times in high mile tranny's the rear clutch seals are worn which will cause your condition. Pressure testing will help pinpoint your trouble. Do you have access to a FSM and test gauge?
Mike

When the problem occurs try putting it into reverse, if it goes in with no issues and then when you re-try drive it still wont go in it is most likely a problem with the forward (rear) clutch pack, either in the clutch or the oil supply to it - presuming your shifter is correct.