Correct thermostat housing for 72 LS5?

[Mike E.]

October, 1971 build date. What would the correct casting number be on the thermostat housing, and what would be the correct location of that number? And what would the correct bolt head markings be?
Thanks!

[Joe L.]

Re: Correct thermostat housing for 72 LS5?

October, 1971 build date. What would the correct casting number be on the thermostat housing, and what would be the correct location of that number? And what would the correct bolt head markings be?
Thanks!

Mike-----

1) Casting number is 3877660. However, it's also possible that some cars received a GM #3972128. The difference between the two? The 3877660 has a tab extension on the base for an accelerator return spring (not used on Corvette applications) and the 3972128 does not.

2) Some claim that the casting number location for the outlet was on the base for big blocks. I question that was true in all cases. The specs for the 3877660 outlet call for the number to be on the neck. However, some 3877660 outlets definitely have the number on the base. Whether this type was used on all big blocks, I doubt. The 3972128 definitely has the number on the base. I've never seen one with it on the neck;

[Mike E.]

Re: Correct thermostat housing for 72 LS5?

Now that all you guys are back from Carlisle: any more input?

[Bill C.]

Re: Correct thermostat housing for 72 LS5?

myt 72' had the 660 housing.
4/15 build. original to the car.

[Peter S.]

Re: Correct thermostat housing for 72 LS5?

Hi Joe,

I have noticed two casting number locations for the 3972128, albeit both are on the base. The first picture is a 128 housing that is a known original off of a '71 base model. The second is a 128 housing that came off of my 1971 L46 CE motor. The third picture shows a thicker flange at the stud location for the 128 than the 660. I have not seen many pictures here on the TDB of the 128, so I thought I would share.







Peter

[Harmon C.]

Re: Correct thermostat housing for 72 LS5?

I have not seen a 128 stamped by the hole on a corvette but I have not seen them all.

[Owen L.]

Re: Correct thermostat housing for 72 LS5?

Mike-----

1) Casting number is 3877660. However, it's also possible that some cars received a GM #3972128. The difference between the two? The 3877660 has a tab extension on the base for an accelerator return spring (not used on Corvette applications) and the 3972128 does not.

2) Some claim that the casting number location for the outlet was on the base for big blocks. I question that was true in all cases. The specs for the 3877660 outlet call for the number to be on the neck. However, some 3877660 outlets definitely have the number on the base. Whether this type was used on all big blocks, I doubt. The 3972128 definitely has the number on the base. I've never seen one with it on the neck;

Is this info still correct after 6 years? My 3877660 has the # on the base but is broken in the neck -- someone probably pried against the aluminum with a screwdriver to break the hose loose. Any more developments with the application of 3972128 on '72s?