Your tractor is a 1990 to 1993.
If you want a OP and service manual for it give me a shout I have both.
What model do you have a DT, a DT-GST, or a DT-WET ?
If you don't know, what letter logo's are on the tractor.
They all have specific problems with overfilling the case.
Was the case low or empty?
Did you drain it back to where it should be?
Is it leaking hydraulic fluid from under the bell housing?
In the picture is the bell housing drain (yellow) it will look like a nut with a pin hanging out of it, pull that drain out and see if there is any fluid in there.