I'm going to wade into this ,I am just finishing rebuilding my 62. 261 it has the original thermo housings PN 3764749 & 3764748 I didn't get to see how all the hoses were routed,head was off engine when I bought the truck.I have read all the threads ,read all Deves info on his site and I'm still not sure how this all goes together. I purchased the 3 piece napa thermostat and was trying to fit it this afternoon,it seems it will work,it seals off the upper housing ,and allows coolant to by-pass from the upper housing back to water pump until the t-stat opens and then majority of coolant will flow to rad. The question I have is what about the heater circuit, it is by-passing from the lower Tstat back to water pump uncooled all the time? Or at least all the time the heater valve is open. Or am I wrong?
