The MR2 seats I installed in this '86 fit the outer 2 holes and the seat belt bolt hole.
The truck originally had a bench seat, so You might get lucky and all 4 mounts will line up.

The one thing that I have noticed with the Toyota buckets from auto to truck, is that you have to lift the outer rear mount so the seats backs are level, something I didn't do on the '86. Sometimes it is as simple as a few washers and others it can be a 1" spacer, as with the '94 Supra seats in my '91. At any rate for $10ea. they are a steel and it wont take much to get them to fit if they aren't a direct bolt in. If the mounts don't line up exactly, you could try and swap the seat mounts from the Runner's seats to the MR2's.