I did a little searching but didn't find anything about it so I thought I'd share. Since I redid the Cadillac's engine, a 1957 365 c.i., punched .030 and a little head work, Its run about 210 degrees constant. Good coolant, rebuilt water pump, stock fan & a cleaned original 53' radiator with a 9-LBS cap. Its never overheated, never had an issue, but I always wanted it a bit cooler. So while at the NAPA that did my engine work the other day I was looking at the Mr. Gasket section, (Needed valve cover hold downs for my dads 63' Impala), I noticed the 180 degree Big block Mopar high flow stat. Had them grab a 57' Cadillac O.E.M. thermostat off the shelf and measured them, identical diameter. Got home, test fit it in the car, bolted it all back together & topped it off. 185 is the max it will go. I haven't had a chance to test it out more with some driving but I thought it was worth mention, considering the ease of dropping a few degrees off the gauge. Hope its useful!