Hello Castrol. The gens are different for the trucks than they are for the 4Runners.
As Braden pointed out the 4Runners are '84.5 to '89 for the first gen, then the rest of his info is right.
The trucks are:
79-83 1st gen truck
84-88 2nd gen truck
89-95.5 (pre-Tacoma); 3rd gen truck
95.5 Tacoma would be the 4th gen
I think the last two are correct of the Tacoma was introduced in mid '95.
Brian has some well detailed info here
too.