EXTENDED STORAGE OF A REBUILT 727

My son has a72 fury wagon, came with an incomplete 318 in it, (basically a short block) the last renewal was 1979. He bought an 83 D250 (used to be mine) back from the guy I sold it to. The KD was laying on the intake, we have no idea how long, just that it was connected and working as intended when I sold that truck over 10 years ago.
So we had "cold feet" about using the trans out of the truck. He took a chance on the one that came to us in the wagon, pulled the pan and did fluid/filter, put the engine out of my old truck in front of the car's trans, and crossed fingers. So far that 727 that has sat apparently since 1979 is surprisingly working just fine. He wants to go thru the one that came out of my old truck when we have time and have it here as a "backup". Though I don't think he'll put 3000 miles on that wagon this year...... The one In the car date codes out to the same time the car was first built, and I know for sure that the one out of the truck was original to that truck.
I was quite surprised the one from the car took off and appears just fine after having sat that long.