There is an entire line of Trooper (Bighorn) that came with Recaro seats as standard trim, from 1st gen. right through to the present model. They are the 'Irmscher' line. There should be seat brackets available for most (not all) Recaro setas that will match the hole pattern in the Troopers, therefore...if you could find a 1st gen. that had the seats in a junkyard. Old vehicles sent out of Japan lose the seats pretty quickly, but the brackets are usually left there.

I don't know why, but I have it recorded here in my notes that '81 to '84 Bighorns with Recaro seats use the baseframe bracket no. 84.051.0, on both the left and right side.

Probably not the answer you wanted...