Actually the 143 (or 140) degree thermostat is the salt water version AFAIK.
The 160 came later for fresh water use. Not sure if retro back to '94 for
me, as they still list the 143.

"Calif Bill" wrote in message
ink.net...
If boating sal****er, the temp is normally 160. But fresh water, you
could
raise the temp to 190 and get better performance / milage. The 160 stops
precipitation of salt on to the engine cooling passages. Go to a decent
auto parts house and ask for a 160 or 190 thermostat for a 5.7L Chevy. Or
take the old one with you.
Bill

"OSU" wrote in message
ervers.com...
whats the correct operating temp for a 98 Merc 5.7 V8 RWC Carb pushing
an
alpha drive, and whats the correct T-Stat for this engine

Thanks