Where we these used other than the thermostat housing?
Intake manifold and water pump as far as I know.
The intake is "M". The water pump bolts are "TR". How about the alternator bracket (3 total) to water pump?
TR head markings were used in a number of locations including accessory mounting and manual transmissions ( mounting to bell housing, side cover ).
Steve
Also on rear drum brake backing plate to axle carrier.
Arno