Drivetrain 1991 Mustang Convertible Lx

I have a 1991 Convertible 2.3L LX with a A4LD trans (# P86gt-7006 AAR 1-5542 D 38.50800 stamped on the body. I need to rebuild it, but when I run the number to ensure proper ID, I get every other ford transmission but this one. What am I doing wrong?

Jim Cramer

Called Ford, was told I should have a 91GT MUB trans according to VIN. They have zero info on that transmission.