I understand the upgrading idea, but how much fab work do you want to get into?Seeing as your 88 is a 3.0 the 3.4 is basically a drop in swap, with the exception of the wiring. If your's is a manual then the 3.4 with a 3.4 clutch bolts up to the existing transmission with no problems. If manual then your transmission is a R150F, if you go to a 3RZ-FE, you either have source a "w" series transmission and gear transfer case, or you can buy a bellhousing from Toyota ($380.00), that will allow you to bolt a 3RZ-FE to your "R" series transmission. You will also have to fab motor mounts and probably will have to move your transfer case crossmember, new drive shaft and of course there is the wiring to take care of as well.
It comes down to how complicated you want to make your swap and if your truck is an auto....your swap just got more complicated.
Last edited by Hadmatt54; 12-03-2012 at 02:57 PM.