The 180 degree replacement (63mm) thermostat is the Stant Thermostat #13078.dtpracing said:
For those who would like a failsafe unit this heavy duty "170" degree European-made stat is a good one (both that I've used run at 176 EVIC degrees, BTW):
Prestone 383-170. Available at Checker / Kragen / Schuck's Auto Parts stores. Made in Germany by Cooper Standard/Robert Shaw.
63.5mm vice stocker's 63mm. Requires small flat blade driver, or similar, to help tuck rubber gasket into receiver due to slightly tighter fit.
Heavy Duty, has brass dog-bone wobbler in air bleed hole. (Orient bleed hole to highest point of the thermostat during install.)
Fail-Safe feature insures thermostat valve moves to full open position in event of a failure.
This unit is more expensive than the 180s have been. It's obviously more heavy duty, and the failsafe feature alone makes it worth the price of admission for me. I paid $16.99 or so in California at Kragen's for the one I bought for CoolVanilla's car at GIFO3 recently, $18 & change here in Arizona at Checker for the one(s) I bought to put in mine. It's marginally more difficult to install due to the tighter fit.
GIFO3 showed a gain of 5hp/3tq at the rear wheels on back-to-back 3-run series dyno runs, 170 vs. stock 203 degree stat.
Best to change this one when the motor's not hot as it requires more fingers in the pie to get it seated.
