First, some info, as Panteras are the MOST modified sportscars on the face of the earth, so yours is likely not stock. Stock watertemp gauges are notoriously inaccurate, especially if mounted in the location DeTomaso picked (in the swirl water tank near the rt cylinder head). If the gauge sender is located there, it should be moved ASAP to the block, under the thermatat housing (Fords stock location for 351Cs). The gauge wire will reach the new location, and the plug in the block will fit the tank, making this a no-cost swap. Second, this engine takes its own special version of a thermostat, and no others will work.If your hearimg is sensitive, you may hear water moving back & forth in the big water pipes under the console. Third, the car came with two small pusher fans mounted in the grille opening ahead of the radiator, so your 3rd fan is an add-on. The stock fans were wired to turn on via separate thermostats (one @ 180, one @ 192 degrees) in the radiator header tank, but many cars were rewired so the fans turned on manually, usually by the normally-unused lowest switch on the console, or even by the ignition switch. There are two "cannisters"- the smaller one is a swirl tank that contains the radiator pressure cap, and a second, larger one is an overflow tucked underneath the rt side engine cover and only has a cap that does not seal pressure. Finally, your car appears to be a '74 from your 'handle,' so your gauge reads to 260. An operating temp of 220-230 degrees around town is not overheating; overheating is defined as when coolant burps out of the small tank, usually after a long slow run in traffic. On the highway, operating temps will run around 180-200, assuming the gauge reads half-way correct. Oh, and you'll have more questions.... I recommend buying ALL the manuals etc on Panteras you can find, as you appear to be a do-it-youself guy, and without a 'cookbook' to follow, this will not turn out well. Elsewhere in this website are all known manuals.
