Welcome to TRS
2003 dash is not micro-processor controlled like later years
It has very little interaction with PCM(ECU)
The temp gauge and PCM shared one ECT sensor, but older engine will have separate SENDER for gauge and Sensor for PCM, so you can wire it that way.
CEL(check engine light)
OverDrive on/off light
4x4 lights
Check gas cap light
Are the other connections from PCM to dash
It also monitored fuel level but wasn't involved in gauge display
So just the CEL and Temp gauge need to be dealt with
Ford changed to oil pressure SWITCH in the late 1980's, so if oil pressure is above 5psi then gauge shows "normal" range, it doesn't go up or down, it is ON or OFF, and this is just 1 wire from SWITCH on engine to the dash.
Many like to have "real" oil pressure gauge, also oil temp if you run a Turbo, but up to you.
You will have electric speedometer, it needs 8,000PPM(pulse per mile) AC voltage signal from a VSS(vehicle speed sensor), if the T5 has a worm gear speedometer drive gear on the tail shaft then you can use a Ford VSS and change the Driven gear to calibrate speed shown same as speedometer cable setup.
You will need to change the wiring for this, as the 2003 VSS was not gear driven and outputted about 15,000PPM which went directly to PCM, PCM then converted it to 8,000PPM and sent it out to speedometer and cruise control.
Worst case would be to spend $85 on an SGI-5E:
http://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=126/category_id=311/mode=prod/prd126.htm
It can be spliced into the Rear ABS sensor wires on the axle VSS and then convert its signal to the 8,000PPM needed by speedometer
Best to look on Mustang sites for best PCM to run with turbo 2.3l Lima engine, 2.3l was also stock engine in Mustangs and those owners were alot more avid about turbo swaps than Ranger owners which are more 5.0l V8 swap oriented
Good resource page here, bookmark it:
http://www.therangerstation.com/tech_library/index.shtml
Look in Engines section, a few articles on turbo 2.3l swaps and wiring
I posted the 2003 Ranger dash cluster wiring in this thread, go there to download it:
http://www.therangerstation.com/forums/showthread.php?t=166819