before changing my coolant my engine would heat up to the center of the meter(190 i guess?) and it would stay there nice and steady. after changing my coolant the temperature would shoot past 190 to the end of the shaded bar and then suddenly drop back to 190. it only happens on the first heating of a cold engine. i was reading posts and i read that there is a new updated thermostat but with something of an o-ring, and another 180 thermostat. which one should i use? and does anybody have the part #'s off hand?

 

Check the Tech Facts section at the top of the page.
https://www.dieseltruckresource.com/...n&onlynewfaq=1
Click on down load attachment and you'll find great stuff like this..........


Thermostat for '98-'99
MOPAR - 05015090aa
CUMMINS - 3935811

 

is that the standard one? i was looking for one of the better ones...i remember reading somewhere it was cheaper...like 15 bucks.

 

When I replaced mine, I just went to the Cummins parts counter and told the guy that I wanted a 180* thermostat for my Dodge 5.9.