HELP 87 V-6 2wd into 89 V-6 4WD ?

Help I have a wrecked 87 2wd 3.0 V6. I also have an 89 4wd 3.0 V-6. And I'm in hopes that the motor from my 87 is a straight drop in!! but I'm afraid it isn't because of little bits of info I've seen ie; different oil pump #'s and also a different water pump! someone please help!