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Got an aluminum bell housing painted Chebby orange the other day at a garage sale - owner didn't remember what it came off - the only numbers I can make out appear to be a casting number - appears to be 464697 - any help?
The 464697 casting number bell housing can be one of two finished part numbers. One of them is the GM PART #464697. This bellhousing was used on many S-10 and Blazer light trucks, but on no passenger cars.
The other bellhousing made from this casting was the GM #3899621. This bellhousing was widely used on Corvettes during the 67-81 period. All Corvettes during this period that were equipped with 14" flywheels used the GM PART #3899621 bellhousing. Some built during the later 70's also have the 464697 casting number. Most Corvettes (and other Chevrolet cars) with the 3899621 bellhosuing used the 3899621 casting number.
So, how does one tell them apart? Well, there is only one difference in these bellhousings with 464697 casting number----the location of the tapping for the cluth fork ball stud. The 464697 has an "elongated boss" on the inside of the bellhousing. My recollection is that when the tapping is on the upper portion of the boss, it's a 3899621 finished bellhousing; when it's on the lower end of the boss, it's a 464697 finished bellhousing. I might have that reversed, but I think this is correct. In any event, with the 3899621 bellhousing, the ball stud tapping centerline is "centered" with the fork hole in the bellhousing. With a 464697 finished bellhousing, I believe that it's offset.
The flywheel that I decribed earlier does not work with this bellhousing, regardless of which finished part number the bellhousing is. Either the 464697 or 3899621 are designed for use with a 14" ,168 tooth ring gear flywheel. All big blocks used a 14" flywheel EXCEPT 1965 L-78 and 1967-88 L-88/ZL-1.
The 3856579 flywheel is a 12-3/4" flywheel. It requires a GM casting #3840383 or 3858403 bellhosuing. As I mentioned, this flywheel was used for the 1965 L-78 and 67-69 L-88/ZL-1 applications (as well as 70-72 ZR-1 small block applications).
Flywheels (for 2 piece rear seal applications) and bellhousings are generally interchangeable among small blocks and big blocks with the exception of flywheels for externally balanced engines (454 big block and 400 small block).
OK, I see what happened here. So, forget everything I said previously about the "3873456"; I was actually describing a GM casting #3856579 which is the 12-3/4" 153 tooth flywheel used for 1965 L-78, 67-69 L-88/ZL-1 and 70-72 ZR-1.
I think that you will find that the casting number you have is 3973456. This is a 14", 168 tooth flywheel designed for use with an 11" clutch and the GM PART #3899621 bellhousing (which MAY have casting number 464697).
Is the flywheel you are speaking of "dual drilled" for 2 different size clutches? If so, it will have 2 sets of six drilled and tapped holes.
It also occurs to me now that I forgot to provide the application information for the 3973456 flywheel. This flywheel is applicable to 1966-68 Corvette big blocks, except L-88. It's also applicable to all 69-81 Corvettes, small block and big block, except 69 L-88/ZL-1, 70-72 ZR-1, 71 LS-6, and 78-79 L-48. It will be applicable to 78-79 L-48 IF it is dual drilled. It was used in PRODUCTION for 1970 and later applications and is SERVICE for the pre-1970 applications I mentioned.
The GM CASTING #3973456 flywheel was issued in late 1969 as GM PART #3973453. In late 1975 it was replaced by GM #3998281, but the 3998281 may still carry the 3973456 casting number. Later, it became GM PART #3988759 and GM #3991469 which remains available to this very day.
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