C2 66 Bellhousing

[Bill Farmer]

I currently have a scatter shield on my car. While the engine is out no better time to replace the bellhousing. I found a 403 bellhousing at a local salvage yard. I know 621, 444, and 403 are on 66s. Is this a correct bellhousing? My car was built in May. Thank you

[William C.]

Re: C2 66 Bellhousing

Bigblock or smallblock?

[Bill Farmer]

Re: C2 66 Bellhousing

Big block. In Nolan Adams book it had 1 L72 with a 403.

[William C.]

Re: C2 66 Bellhousing

L-72 uses an 11 inch clutch, 621 is only bellhousing that will work with teh correct flywheel and clutch assy.

[Joe L.]

Re: C2 66 Bellhousing

Bill-----

That 1 1966 L-72 that Noland found must have been one that someone converted. 1966 Corvette big blocks all used a 14" flywheel, 11" clutch, and GM #3872444 bellhousing. The 1966 Corvette L-88 would have had the 12-3/4" flywheel and used the GM #3858403 bellhousing, but that option was cancelled for 1966. So, unless Noland found an L-88 masquerading as an L-72, I don't think the bellhousing was original to the car. Changing out the flywheel (and, consequently, the bellhousing) to the 12-3/4" unit was once a fairly popular thing to do in order to get the "high winding" lightweight flywheel. These were originally used for 1965 L-78 and all L-88 but were not used for any other Corvette big block. I wouldn't rule out the possibility that a VERY early 1966 L-72 used the 12-3/4" flywheel and '403' bellhousing, but I sort of doubt it.

The GM #3872444 bellhousing is one of the most difficult of all Corvette bellhousings to find (and, of course, one of the priciest). The rarest Corvette bellhousing is the 1960-only aluminum. The second rarest is the '444'. A lot more of these were made, though, than were made the 1960-only aluminum. The '444' was also used for other 1966 Chevrolets with big blocks (mostly Chevelles) and was also used very early in the 1967 model year, too.

The GM #3899621 bellhousing which replaced the 3972444 is virtually identical and will SERVICE all 1966 Corvette applications originally using the '444'. It's not "correct", but it's 100% functional. The only differences are the casting number and the configuration of one of the reinforcing ribs at about the 10 or 11 o'clock position.

[Bill Farmer]

Re: C2 66 Bellhousing

Dammit!! I thought I had saved some money. Back to the search. Thanks for the info fellas. Bill

[Joe L.]

Re: C2 66 Bellhousing

Bill-----

The '403' bellhousings are pretty common and usually about the least expensive of all Corvette bellhousings. The '621's, on the other hand, are usually pretty expensive. I could never quite figure that out since the 403 was pretty much only used during about 1964 to about 1970 (64 to 68 on Corvettes and 64 to about 1970 for other cars). The '621' was widely used from 1968 onward on just about all Chevrolet car models. So, you'd think that this would be the common and cheap one. But, it isn't.

[Bill Farmer]

Re: C2 66 Bellhousing

I see the 444 selling for around $300. Does that sound about right?

[Joe L.]

Re: C2 66 Bellhousing

Bill-----

Yes, that's in about the right range for an average example. On eBay, of course, one never knows. However, I wouldn't pay more than that for one since, eventually, you should be able to get one for that price. This is ONLY if you want exact, original configuration for judging purposes. As I say, the '621' will work PERFECTLY and differs only with respect to casting number and the rib I mentioned. The rib is pretty much indiscernable mounted in the car. So, the casting number is really all you're getting for the extra bucks. I don't even know if it's judged. The '621' goes for about $150-200, and, perhaps, higher, depending on how foolish eBay bidders are. With bellhousings, though, one must always be on guard for cracked parts. Sometimes, these cracks are hard to discern. The "ring test" can SOMETIMES give a clue, though. However, while you can see the parts on eBay, you can't "hear" them.

The key thing to remember when bidding on eBay is this: most used Corvette parts are available from various Corvette parts vendors at fairly "set" prices. With respect to most used parts, you should be looking on eBay only for bargains (i.e. prices below the going rate, so-to-speak). It's absolutely idiotic to bid used parts up to prices that exceed what you can just call a used parts vendor and purchase it for.

I don't follow the used Corvette parts market-place too well. I rarely look at any used parts on eBay, anymore. However, I see folks all the time bid up new/NOS parts to prices far above what they could just call a vendor and purchase it for. Even NOS parts have a "market value". This means that there is a price that you can purchase them for from established parts vendors. So, why pay more than that price? I'm not usually regarded as a "cheapskate" (more like a spendthrift) but I NEVER bid more for a part than I know I could purchase it for elsewhere. I mean, why would anyone do that?

[Tom P.]

Re: C2 66 Bellhousing

You missed one.
The 464697 is nearly an identical clone to the 444 and 621 housings. I was a later housing than the 621. Other than the casting number, the 464697 is undetectable EXTERNALLY from a 621 (has the same rib configuration. The difference between a 621 and 697 is the boss on the INSIDE for the ball stud. the boss on the inside of a 621 is round (o). The boss on the inside of a 697 is oval (0). I presume the difference in the shape of the boss of the 697 was to allow drilling and tapping of the hole for the ball stud in a differnt position depending on application. The 697 housings were apparently common on later 80s and 90s vehicles and were also a parts replacement housing. If you come across a 697 with the ball stud hole in the correct position, they seem to be REAL cheap.
And an added comment (actually a slam at the sellers of Corvette parts) about the prices of 621 housings. I have FREQUENTLY bought 621 housings at local swap meets for $25-50, but at Vette swaps (or a Vette owner who is selling one), they are gouging people for $150+!!!! So, DO NOT buy parts that are common between Vettes and Chev pass cars from a Vette person. Prices are ALWAYS jacked up on Vette parts that are common to pass cars. I have a 444 housing that I bought a few years at the Chickasha swap meet for $25!!!!! What am I going to do with it? Heck I don't know. Probably sell it to some deserving person someday for $50 (but it will be a Chevelle owner, not a Vette owner).

[Joe L.]

Re: C2 66 Bellhousing

Tom-----

Yes, I was aware of the '697'. In fact, there's an interesting history here. ALL Corvettes with 14" flywheels during the 69-81 period used a GM PART #3899621 bellhousing. However, not all GM PART #3899621 bellhousings have the 3899621 CASTING number. Beginning about 1978 or 1979, many GM PART #3899621 bellhousings, including SOME of those used in PRODUCTION, had the 464697 casting number. Externally, the 3899621 and the 464697 are absolutely identical, except for the cast-in number, of course). The difference is, just as you describe, the boss for the ball stud. The 3899621 has a round boss which can only be drilled and tapped in that location. The 464697 has an oblong boss that can be drilled and tapped on either end. If it's drilled and tapped at the UPPER position, then the bellhousing becomes a GM PART #3899621; if it's drilled and tapped at the LOWER position, then it's a GM PART #464697. That's right, instead of using a non-finished part number for the casting number (so that it would more "key" someone that it could be one of 2 possible finished bellhousings), GM used the same casting number for the PART number of a finished bellhousing. I'll bet this little "foible" has caused folks UNTOLD confusion and problems. So, there are NO GM #3899621 bellhousing CASTINGS which are anything but a GM PART #3899621 bellhousing. However, GM #464697 CASTING number bellhousings may be EITHER a GM PART #3899621 OR a GM PART #464697. The GM PART #464697 bellhousings were used for some later 70s-early 80s truck applications like Blazer, etc.

The "truck guys" are the ones that will most often get "bit" by this. If they need a 464697 bellhousing and go out and find a used one and install it in their truck, they may get a surprise. Keep in mind that the 3899621 PART NUMBER bellhousing is NOT a rare, Corvette-only piece. They were used on MANY Chevrolet passenger cars from 1967 onward and the SOME of the later 70's examples had the 464697 CASTING number. These are the ones that will "fool" the "truck guys".

Corvette guys get "bit" somewhat, too, by this. A Corvette guy just looking for a functional replacement bellhousing and not caring about "numbers" figures that he has to go out and find a bellhousing with the 3899621 number cast on it. That puts him in direct competition with the guys that will pay anything to get correct "numbers". Also, the supply of GM PART #3899621 bellhousings WITH THAT NUMBER CAST UPON THEM is really a lot smaller than the actual number of GM PART #3899621 bellhousings out there. Most don't know that all they have to do is to find a GM #464697 with the ball stud drilled and tapped for the UPPER position, and they've found what they need. The 464697 bellhousings usually sell for "peanuts" at swap meets. Many of these are actually GM PART #3899621 bellhousings (much to the consternation of the "truck guys" buying one thinking that it's right for their truck).

[Tom P.]

Re: C2 66 Bellhousing

That is a true statement(s)(s)(s)(s)(s)(s).