Ok, so I did a little more digging in the following sections...
1.153 Upper Housing
1.251 Lower Housing
1.246 T-stats
NOTE, Casting Numbers are the same as Part Numbers unless noted otherwise.
My 1959 Parts Book has;
1959 Series 6 (6-cyl)
Upper 3757230
Lower 3757233
T-stat 3144583, 160* Bellows type
My 1960 Parts Book has;
1959 Series 6 (6-cyl)
Upper 3757230
Lower 3764748
T-stat 3144583, 160* Bellows type (1st design)
T-stat 3139133 T-stat unit w/gasket 160* (Harrison) (2nd design)
1960 Series 60 (6-cyl)
Upper 3764749
Lower 3764748
T-stat 3139133 T-stat unit w/gasket 160* (Harrison)
My 1963 Parts Book has;
1959 Ser 6, 1960-62 Ser 60 (6-cyl)
Upper 3764749
Lower 3764748
T-stat 3144583, 160* Bellows type (1959 1st design)
T-stat 3150671, 160* poppet pellet type w/ gasket type (1959-61 ALL 2nd design)
T-stat 3139134 T-stat unit w/gasket 180* (Harrison)...looks like the 160* Harrison was dropped on or before 1963.
My Comments;
It apears the 1959 2nd design T-stats made them a universal size as they are now available for "ALL" series 6 & 8 Cylinder trucks.
I also found in the 1960 book that the Upper Housing Casting was used twice;
1959 Ser 6 (6-cyl) Cast 3757230 (pn 3757230)
1959 ALL (exc. 10F) (1st design) Cast 3757230 (pn 3757238) use with T-stat 3144583.
Deve asked "Don't the holes we drill in the thermostat allow water to pass the thermostat as well?"
Yes, technically that is a T-stat bypass, but it's not flowing coolant back to the engine, it's flowing it to the radiator which is not aiding to engine warn-up or preventing hot spots (flow is to small to do that). It's always been my understanding that the small hole in the T-stat was the bleed off any trapped air when refilling the engine with coolant.
It's my guess that if you use the Bypass hose then you would use the Bi-Valve T-stat and if you blank the bypass then you would use a standard T-stat. I bet there was a 1959 Service Bulletin that covered all of this.
Clear as mud, right?
Mike B
