660 Thermostat Housing - Neck vs. Outer Lip

[Pacecar]

Would anyone have a definitive answer as to why some 660 thermostats have the number marked on the outer lip while other housings have it on the neck. My 04C car has its original and it is on the outer lip. My 06A car is unknown as to originality but has the number on the neck. Thanks

[Mike S]

I believe I read about that on a Chevelle site. In 67 the numbers appear on the lip. I think it was late 68 that it appeared on the neck. I'll see if I can find the article. Both of my 67 L35's have the numbers on the lip.

Update: See reply #16 here: https://nastyz28.com/threads/thermostat-housing.70586/page-2

Update again:  This is one of the Chevelle threads. See reply #4: https://www.chevelles.com/threads/correct-thermostat-housing-65-l78.949354/


Mike