Just recently my 1987 Delta 88 3.8L V6 oldmobile had a transmission
failure. The engine appears fine so I do not believe that to be the
problem.

No warning or anything and now I have no drive in any gear.

Symptoms:
1. Fluid smells fine, when off and after checking in park motor running
fluid level shows high. The times I've checked before problem level was
high when off (expected) and when running level was correct.

2. After several minutes of driving car loses all drive in any gear.

3. Sound like a 2 cycle string trimmer from engine compartment seems trans
area but not 100% sure, sound is in all gears.

4. Car seems to work again for a short time after turned off and allowed
to sit for a few minutes.

I'm trying to get some idea of what might be wrong and what it may take to
fix it either as a DIY or at a shop.

Tim.

I would try replacing the modulator valve first. Or even check any vacuum
lines leading from the tranny. If it still does it after all that it's
either your Torque Converter or the shift band inside. At that point just
get another tranny. It will cost more to fix it than it would to put
another one in. But check the other things first.