I had the transmission rebuilt for my sons car while it was out, now that the car is done there is a constant large puddle of tranny fluid under the car when parked that is coming from inside the bell housing.could this be the main front seal? I thought the seal would be high enough that it would only leak while running.Thanks for any tips.

Could be front bushing and seal. Could be large pump housing O-ring but Check for too much fluid especially warm.
especially if it does not leak driving and running? does it leak after sitting a while?
Oil pan gasket can cause it to leak down the lower bell housing and drip at front but I'm sure you have checked and know leak is inside bell housing.

As said if the idling in neutral level is OK then unfortunately it will have to come back out

tranny was rebuilt and dry, installed new t.c. and added 7 quarts. when I removed the inspection cover the inside was pretty well soaked with fluid. car going up on stands now.

pulled starter and inspection cover, thought I might get lucky and it would be t.c. drain plug but it is totally dry

vent is in front pump also....any bellhousing leak can be front pump seal,bushing to TC,pump gasket and pump oring...

At times the spring that holds tension on the lip seal can be knocked off during TC installation or even at the time it was rebuilt. Those lip seals should be lubricated before installing the converter.
Good Luck let us know what you find.

With the cover off you can use some sort of spray cleaner in around the housing to get rid of the fluid and then let it sit overnight. If the leak is at the seal you should see a stream of fluid running off the middle where as the o-ring could leak anywhere. This will give you an idea of where to look when you pull the tranny.

Not understanding completely, but if you just installed it with 7 quarts of fluid in it before you fired it, especially, but not always, if it wasn't in neutral, it just blew fluid out the vent. Makes a mess, but no harm done. If it had been running for awhile then started leaking, you have a different problem, seal, pump oring, converter, etc.

Pat

tranny out and it looks like it is coming out from the main seal. it looks like it is leaking around the metal edge of the seal and the housing. going back to the shop that built it in the morning.