I recently acquired a few nice accessories for my Loyale from an older GL. 

I grabbed the map light and the rear cargo light. My question is would I need to run a wire from the battery to the map light spot and rear light spot? Would it be unsafe to splice into an existing circuit?

My second question, is the instrument cluster from the GL with the oil pressure and volt gauge transferrable to my 93 Loyale?

Thanks in advance.

I'm not sure if the wire for the rear light is there, it might be.

The voltmeter and oil pressure can be done.  Think more like putting the GL meter assembly into the loyale.   If you want to be fancy, swap the spedometer to keep the milage.

Get the FSM schematics.   the oil guage wire is the same wire as the switch, just move it to the new sensor.

Map lights: grab the factory wiring and you *should* find a matching plug under your dash for them to be powered from. 

Cheers

Bennie