How much do you enjoy wiring and hacking on plastic? You can do this swap, it's just not gonna be fun. Most people want to go the opposite direction and run the needle style gauges instead of the moonies.
The biggest difference electrically is that the 88-91 clusters have the speed sensor buffer stuff built into the cluster. 92-94 (and 95 although it's the new interior style) use a separate module behind the glovebox. So the wiring is very different, right off the bat. Then whatever 88-91 cluster you get, you'd likely need to recalibrate the speedometer for your axle ratio and tire size, unless you lucked out and got one that was exactly right for your truck.
Then there's the plastic hacking. 92-94 dashboards have a little pedestal in the plastic behind the cluster where the connector fits in. 88-91 does not, as that cluster is deeper, so you'd have to chop out that pedestal to make the cluster fit. Or, you could try to score a whole dashboard out of a 88-91.
Richard
