I saw a 11" bellhousing today and i was wondering if any one knows what it originaly came on?
It looks very similar to a 621 but the complete casting number is 3843942. I can not find this casting number in any of the research books. It is aluminum, and has the small hole for the trans collar same as a 621.
Thanks in advance.

#3843942 is the old-school version of the '621'...
It was used on the Heavy Duty 11" clutch applications from @ 1962 ~ 65. Many of the famous '409's got this housing.
It has the pivot ball provission only on the left side (v.s. many housings which have the tooling holes on both sides for allowing the release arm to be used on the left or right as the application needed)
It has the standard 6 flange bolt holes and also has an extra round 'ear' at the top. This ear may or may not be drilled also, I've seen them both ways.
Bore hole should be standard 4 11/16".
The bottom was cast closed and it used a front mounted inspection pan - one of the first types to use this.
Also this housing requires a block mounted starter use only - so use after 1962 is indicated as there is no provision for mounting a starter on earlier models.
The last use of this casting I know of is the 200 or so Chevelle RPO-Z16's (396/375) - so anyone doing one of those would be thrilled to have it, you may stand to make some money reselling it over at Team Chevelle.
Some Corvettes with Spec. H.P. 327's also used this casting.

Hope this helps;
John

[QUOTE=Vintage 68
Some Corvettes with Spec. H.P. 327's also used this casting.

Hope this helps;
John[/QUOTE]

The 942 bellhousing was never used on Corvettes; all '63-'68 small-block Corvettes ('63 was the first year of block-mounted starters on Corvettes) used 153-tooth flywheels and 10.5" clutches.

:beers:

John, I used to do some work on a couple Z06-L84 C2 'Vette's that had a factory 11" clutch assembly and this housing. I could have sworn this was the original factory set-up for these units and that they used this housing until the '962's came along in the mid 60's.
I know it was used in other HD 11" clutch applications until 1966.
This may be my bad then JohnZ - I'll defer to you on this.

John

My 65 and 66 L79 327-350 hp both had 621 bellhousings and 11 clutches and were M21 both Vette coupes just my 2 cents

My 65 and 66 L79 327-350 hp both had 621 bellhousings and 11 clutches and were M21 both Vette coupes just my 2 cents

Lots of folks swapped them out to use 11" clutches, but no '63-'68 small-blocks ever left St. Louis with 621 bellhousings. Small-block Corvettes started using the 621 bellhousing and 11" clutch in '69, and continued through '81 (except ZR-1).

:beers:

Who knows John I can remember taking a lot of that smog stuff and bellhousings and things off and throwing them in the trash 35 or so years ago. Most of these type of cars led a hard life. We didn't worry about collectability or matching numbers back in those old racing days. If we could only turn back the time on ourselves and the cars!