C3-bellhousing numbers

[Steve L.]

I just pulled my engine on a 73 coupe, manual, L48. The bellhousing has two circles cast in. Both have diagonal lines. One circle has nothing while the other has a 2 on one side of the diagonal and a couple of dots on the other side. These dots look like they may have been numbers or letters that haven't filled in during casting. I've owned this car since new and know that the housing has never been replaced.How can you tell the date? it's impossible to tell what those dots are - they haven't been corrodes off either. The casting is actually poor with lots of knit lines and porosity.

This casting has also been damaged, looks like someone put a jack under it during a clutch replacement and pushed some metal through at the bottom. The pieces are all there. Can it be welded or is it easier to get a proper dated one as a replacement?

Steve L
73 coupe since new

[John H.]

Re: C3-bellhousing numbers

Steve -

The 621 bellhousing didn't have the usual casting date code we're used to seeing on iron castings, nor did most aluminum bellhousings - they're dated like Muncie transmission cases. The circle on yours means that it was cast during the second week (the two dots) of the second month (the "2").

The kind of damage you describe on the bottom is common, and may be repairable, although a swap meet replacement would probably be less costly than a heliarc weld repair. Bellhousing numbers are not a judged item in Flight Judging.

[Joe L.]

Re: C3-bellhousing numbers

John and Steve-----

Yes, the GM #3899621 bellhousing is fairly plentiful in the used marketplace. It was supplied on most 67-82 Chevrolet applications utilizing a 14" flywheel and 11" clutch. However, the ONLY bellhousings that will work for any 67-81 Corvette utilizing a 14" flywheel are the 66-only "444", the "621", and the GM #469697. Of these, the "621" is, by far, the most common. Good used examples can be purchased for $100, or less.

[Steve L.]

Re: C3-thanks *NM*