I would bet an earlt 90s t bird IRS setup would weigh a lot less than the jag. Seems to me the larger portion of the subframe is aluminum. Plenty of them had rear disc brakes.They were also a lot easier to change rotors on also
Made in USA and parts off the shelf even at Mc Parts
An 8.8 was used in the supercoupe and the v 8 cars and some of the standard v 6 models.
Fact is stranger than Fiction