I can't find any rims that fit my truck?

I have a 1975 ford courier and they have pretty small tires/wheels. Bolt pattern 4x108
Diameter: 13.0'' - 14.0'';
Width (inches): 5 - 6;
Offset (mm): 41 - 43.5.

Nothing nice fits. Any suggestions?

"Nice" is subjective. No one can offer anything because we have no idea what you think is "nice".

Be a purist and run stock rims and hub caps. Get the wheels sandblasted and powder coated and find some original caps in immaculate condition.

Your figures are not correct…
bolt pattern - Metric: 6 X 139.7
Standard: 6 X 5.5

OEM rim size - 14x6

I would think that most 6 lug rims would fit… Maybe call some tire stores near you for their info

Read more: Wheel Bolt Pattern Cross Reference Database and Conversion Guide: FORD COURIER PICKUP http://www.roadkillcustoms.com/hot-rods-rat-rods/Wheel-Bolt-Pattern-Cross-Reference-Database.asp?Makes=FORD&Models=COURIER+PICKUP#ixzz4mSBkHpsR