Big difference due mostly to the transmission section of the harness; the '95 will have an electronically controlled transmission (4L60E, not 4L60). The '92 will not (assuming it's a light duty automatic, it will be the 4L60/700R4.)
1995 is also a one-year-only truck in so many ways that I wouldn't be surprised if they changed the engine harness from previous years, they sure changed a lot of other stuff just for 1995.
The only drop-in harness for sure will of course be another 1995 model with the same engine, trans, and drive type (2WD or 4WD)
1994 and 1993 are likely to be very similar but the whole 1995 issue brings things into question so you'll have to really look hard at 'em.
Keep in mind there are 2 main harnesses under the hood. The engine harness which comes through on the passenger side of the firewall, and everything else - which has a junction block on the driver's side of the firewall. That's lights, fuel pump power, ABS unit, basically everything except the sensors/injectors/etc. handled by the other harness. IF that's burned up you'll need the harness from a 1995 only for it to be a drop-in; 1995 truck is first year for 4-wheel ABS on a pickup (SUV's had it since 1992 but it's a different system.)
Richard
