Ihave a 1988 Ram W150 with a 318. I got it about 2 months ago. I will list pictures. Problem is it was running cool. needle would only get up to the 2nd line on the gage. So I got a new 195 deg. Thermostat. As I was replacing it I saw that the old one was a 160 deg. I put the 195 in and now the needle goes the half way spot on the gage. Is it running hot know? Should have I left the 160 in. Which is better for the motor.

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If you are in a hot climate & tow alot, I'd leave the 160. If not, go for the 195 (I think that's the stock temp...check with the parts store). If you don't let the engine get hot enough (exspecily on short trips), the condensation that occurs when burning fuel can aculmate in the oil pan. If it sits, that can cause rust. Idealy, you want the engine to run cool, but warm enough to evaporate any condensation.

 

I think 180 is the factory temp on these older motors. Nowadays everything runs 195.