Just finished working on three bats- they all had aluminum trunks
@Keshav will probably know. I thought later Bats had steel boot lids on account of the down force from the wing. Noting @sfdon 3 Bats they could have come that way new without the rear wing fitted at the time?
I didn't see a vin for this car. It looks to be post-facelift from front valance, but that could be new?