A similar bracket that is actually a weight. In other words, a system to dampen driveline harmonics. I dunno if it was used instead of the transmission weight, or in conjunction with it.
My 8.8 in my 86 SVO had a large weight hanging down that had two bolts running up through a bracket like that. I’m guessing to help with axle wrap up on acceleration although it also had quad shocks. - Matt
As Tom said, it is a NVH damper. My '87 Aerostar had one. The closest it got to being a performance car was when is was parked next to a Mustang at the dealer.