Just what IS the correct thermostat housing for a 1973 L48?

[Linda D.]

The more I read on this topic, the more confusing information becomes. The JG (page 78) says the original housing for a 1973 L48 is PN 336790, but then it goes on to say that the thermostat housing does not have a boss or port in either year (73 or 74). PN 336790 does have a port according to photos I have seen however so this conflicts with the JG. Other previous threads in the forum suggest that PN 3972128 is correct for the 1973 L48....and that maybe PN 3877660 could be a correct number but then maybe not as it could be a service replacement part and not the production line part. My car was built in October 1972 so it is an early run 73. I am looking to bring it back to as close to original as I can. Right now it has an aftermarket chrome housing which absolutely must go. Can any of you guys help me out? Thanks, Linda

[Russ S.]

Re: Just what IS the correct thermostat housing for a 1973 L48?

Linda, I have in my shop right now a 30,000 mile unmolested two owner 73 L48 auto. It has #GM 3972128. There is a depression on the rear side next to the LH (long bolt). On the RH side the base around the area of the bolt is thicker and then gradually steps down both on the front and the rear as you go to the LH side. Hopes this helps.

[Martin N.]

Re: Just what IS the correct thermostat housing for a 1973 L48?

LINDA-
Our 1974 L-48 thermostat housing part number is; 336790. As far as I know this is correct for 1973-1974, 350 L-48 engines. 1975 might be different with a temprature switch mounted in the housing.

Marty

[Linda D.]

Re: Just what IS the correct thermostat housing for a 1973 L48?

Thanks guys. My car has 33000 miles on it which I believe are original, having had the car gone over by 2 local car buffs topside and underneath. I am the 3rd owner, the guy before me started adding aftermarket little chrome touches to it. Fortunately he ran out of money before he did too much "improving", so it is not too far off the mark. Sure appreciate your advice on this, I will doubtless be back for more knowledge in the very near future. I think I will use the 3972128, even though the JG says it is the 336790. From what I understand, this latter number might not have been used on a 73 in production with the port, as the 73 had no need of this. And the 3972128 is closest in design to the 3877660 which is apparently the service replacement part. I guess I will take my chances if I decide to have the car judged at an event because I believe the JG to be in error.

[Patrick H.]

Re: Just what IS the correct thermostat housing for a 1973 L48?

Thanks guys. My car has 33000 miles on it which I believe are original, having had the car gone over by 2 local car buffs topside and underneath. I am the 3rd owner, the guy before me started adding aftermarket little chrome touches to it. Fortunately he ran out of money before he did too much "improving", so it is not too far off the mark. Sure appreciate your advice on this, I will doubtless be back for more knowledge in the very near future. I think I will use the 3972128, even though the JG says it is the 336790. From what I understand, this latter number might not have been used on a 73 in production with the port, as the 73 had no need of this. And the 3972128 is closest in design to the 3877660 which is apparently the service replacement part. I guess I will take my chances if I decide to have the car judged at an event because I believe the JG to be in error.

Linda,

Please submit the info to Brian Pearce as well as Ken Sleeper. They are working on the next edition of the JG and would like your input.

When reviewing the Chassis section recently I also noted several errors.

Patrick

[Harmon C.]

Re: Just what IS the correct thermostat housing for a 1973 L48?

The 128 has been judged correct for years for 73 L-48 L-82 and 454.

[Russ S.]

Re: Just what IS the correct thermostat housing for a 1973 L48?

Thanks Lyle. Good to hear from you.

[Linda D.]

Re: Just what IS the correct thermostat housing for a 1973 L48?

Thanks everyone!