Dorman part number 746147.
It won't ever be extinct. It is the same actuator the Mustang uses (and many, many more Fords), and there will always be a source for the Mustang. Pretty sure Rock Auto would have them as well.
EDIT... Whoooa, I decided to look at Rock Auto and they do have them for 25 bucks. Here's the cross reference of vehicles it came on:
FORD AEROSTAR (1986 - 1991)
FORD BRONCO (1989 - 1991)
FORD BRONCO II (1988 - 1990)
FORD COUNTRY SQUIRE (1987 - 1991)
FORD E-100 (1980 - 1983)
FORD E-150 (1980 - 1991)
FORD E-250 (1980 - 1991)
FORD E-350 (1980 - 1991)
FORD F-150 (1989 - 1991)
FORD F-250 (1989 - 1991)
FORD F-350 (1989 - 1991)
FORD FAIRMONT (1980 - 1983)
FORD GRANADA (1981 - 1982)
FORD LTD (1980 - 1986)
FORD LTD CROWN VICTORIA (1983 - 1991)
FORD MUSTANG (1980 - 1993)
FORD RANGER (1988 - 1992)
FORD TAURUS (1986 - 1988)
FORD TEMPO (1984 - 1994)
LINCOLN CONTINENTAL (1982 - 1987)
MERCURY CAPRI (1980 - 1986)
MERCURY COLONY PARK (1987 - 1991)
MERCURY COUGAR (1981 - 1982)
MERCURY GRAND MARQUIS (1980 - 1991)
MERCURY MARQUIS (1980 - 1986)
MERCURY SABLE (1986 - 1988)
MERCURY TOPAZ (1984 - 1994)
MERCURY ZEPHYR (1980 - 1983)