1995 Ford Thunderbird ECM

Depends on if the 95 has OBD I Or OBD II connector. OBD I covers 92-94 and some 95 OBD II 95-96 and up. If both have the connector under the hood that looks like this on drivers inner fender.

Then probably yes! if the 95 has a connector inside the car under the dash that looks like this, then no.

If the connectors are the same should not be a problem to swap them.

It's OK to use the Mercon V it is a newer formulation, and recommended by Ford for thier cars and light trucks. Her's the Tech Bulliten on it:
MERCON ATF IS BEING REPLACED BY MERCON V ATF AS A SERVICE FLUID TECHNICAL SERVICE BULLETIN Reference Number(s): 06-14-4, Â Date of Issue: Â July 24, 2006 Superceded Bulletin(s): 01-15-7, Â Date of Issue: Â August 6, 2001 Related Ref Number(s): 01-15-7, 06-14-4 ARTICLE BEGINNING ISSUE MERCON(R) Automatic Transmission Fluid is being replaced by MERCON(R) V as a service fluid. ACTION Beginning immediately all automatic transmission / transaxle applications requiring MERCON(R) can now be serviced using MERCON(R) V or MERCON(R) Automatic Transmission Fluid or dual usage fluids labeled MERCON(R) / MERCON(R) V. After July 1, 2007, MERCON(R) Automatic Transmission Fluid will no longer be manufactured, therefore, availability of this fluid will only continue for however long it takes to deplete what remains in inventory. SERVICE PROCEDURE Service automatic transmissions requiring MERCON(R) with MERCON(R) V or MERCON(R) Automatic Transmission Fluid or dual usage fluids labeled MERCON(R) / MERCON(R) V For proper fluid application on current and past model vehicles equipped with automatic transmissions / transaxles refer to the fluid usage chart. ( Fig. 1 ) FORD: 1980-1997 Crown Victoria; 1981-1997 Mustang, Thunderbird; 1981-2003 Escort; 1986-1993 Festiva; 1986-1997 Taurus; 1989-1997 Probe; 1994-1997 Aspire; 1995- 2000 Contour; 1980-1996 Bronco; 1981-2003 F-150; 1981-2004 E-Series, F-Super Duty; 1983-1996 Ranger; 1986-1996 Aerostar; 1991-1997 Explorer; 1993-2004 F-53 Motorhome Chassis; 1995-1998 Windstar; 1997-2004 Expedition; 2000-2005 Excursion; 2001-2007 Escape; 1987-2000 F- & B-Series; 2000-2007 F-650, F-750 LINCOLN: 1980-1997 Town Car; 1981-1997 Continental; 1993-1997 Mark VIII; 1998-2004 Navigator; 2002-2003 Blackwood MERCURY: 1980-1997 Grand Marquis; 1981-1997 Cougar; 1986-1997 Sable; 1987-1999 Tracer; 1995-2000 Mystique; 1999-2002 Cougar; 1993-2002 Villager; 1997 Mountaineer; 2005-2007 Mariner MERKUR: 1985-1989 XR4TI NOTE: This article supersedes TSB 01-15-7 to update the vehicle application chart. CAUTION: AUTOMATIC TRANSMISSIONS / TRANSAXLES THAT REQUIRE MERCON(R) V SHOULD STILL ONLY USE MERCON(R) V ORDUAL USAGE FLUID LABELED MERCON(R) / MERCON(R) V. CAUTION: MERCON(R) SP, MOTORCRAFT PREMIUM AUTOMATIC TRANSMISSION FLUID AND MOTORCRAFT M5 ATFS ARE UNIQUE FLUIDS AND MUST BE USED IN APPLICATIONS RECOMMENDING THAT PARTICULAR FLUID. USE OF ANY OTHER FLUID MAY CAUSE REDUCED FUNCTIONALITY OR TRANSMISSION DAMAGE. CAUTION: THE FUNCTIONAL CHARACTERISTICS OF FLUIDS FOR CVT TRANSMISSIONS ARE VERY DIFFERENT THAN THOSE OF OTHER AUTOMATIC TRANSMISSION FLUIDS (ATFS). USE OF A FLUID OTHER THAN MOTORCRAFT CONTINUOUSLY VARIABLE CHAIN TYPE TRANSMISSION FLUID OR ONE LABELED AS MEETING MERCON(R) C WILL CAUSE FUNCTIONALITY CONCERNS AND INTERNAL TRANSMISSION DAMAGE. CAUTION: DO NOT USE AUTOMATIC TRANSMISSION FLUID SUPPLEMENTS, ADDITIVES, TREATMENTS OR CLEANING AGENTS.