All 621 bellhousing identical??

[Steve L.]

These housing seem to come out of a number of vehichs and can be found in driveline, ebay etc. Are they all the same and is the factory machining all the same? Need to replace my slightly damaged one on my 73

Steve L
73 coupe since new

[Joe L.]

Re: All 621 bellhousing identical??

Steve-----

The GM #3899621 bellhousing was used on MANY Chevrolet applications from 1967 to 1981 and, perhaps, even after that time. Virtually all Chevrolets during this period that were equipped with 14" flywheels and 11" clutches used this bellhousing or virtually identical bellhousing of GM casting #469697. The '621' is, by far, the most common, though.

Functionally, all '621' bellhousings are FULLY interchangeable. In terms of general configuration, they are all identical. In terms of fine nuances, there may be slight differences. The only differences that I've observed on these (and I've looked at a LOT of them) is the font style of casting/part number and the circular casting mark with "dots" ("date stamp", but includes NO year of manufacture information). The circular mark is not always present.

I'm sure that GM manufactured or had manufactured MILLIONS of these bellhousings over the years and there were likely many molds, each having its own "individual" characteristics. Plus, the molds were likely refurbished many times over the years and that added other slight differences. So, I'm sure that there are many slight variations out there.

[Steve L.]

Re: All 621 bellhousing identical??

Thanks Joe,
So as a correct replacement for a 73, it sounds like it doesn't make much difference which 621??

Steve L
73 since new

[Joe L.]

Re: All 621 bellhousing identical??

Steve-----

Yes, I'd say so.