I got a 12bolt housing and on the tube its stamped cf and i checked on this site to see if its a posi. The rear numerical codes has it listed as cf x 3.31 12 bolt iam hoping the x under positraction means it is a posi rear can anyone help with this thanks.:hurray:

CCF is the code for a 12 bolt 3.31 posi

I tryed to look that up but the chart on this site has just cf - x - 3.31 - 12 bolt is there another chart to look this up so its not a posi or can i make it one thanks.

Drop the pan and take a look. It probably needs new oil anyways.:thumbsup:
These cars are around 40 years old. God only knows what has gone in and out of that rear. My own 69 Green on Green came with a 6cyl and PowerGlide. I thought I had some were around a 3.73 non-posi. I pulled the pan and found a
2.55
CAR HAS BEEN SITTING FOR 11 YEARS...
http://www.chevelledotcom.com/plugins/p17_image_gallery/images/1433.jpg
This is my next project.

I got the numbers off the housings there 3775--- - d186 - gm1 can anyone help with this my question is if its not a posi can i make a posi thanks.:hurray:

I got the numbers off the housings there 3775--- - d186 - gm1 can anyone help with this my question is if its not a posi can i make a posi thanks.:hurray:
Man didn't you read my post...

Those numbers will only tell you what used to be in there but nothing about what's in there now, a lot can happen in 40 years. Jack up the rear end and spin the wheels. If it's a posi, both wheels will spin the same direction. You can also check the ratio by counting the number of turns the drive shaft makes per turn of the wheels.

Tom

CCF is the code for a 12 bolt 3.31 posi
so the ccf stamped on the tubes is correct for a posi rear and the cf stamped on the tubes is for none posi units can i make it a posi or do i have to get the right housing to hold the gears or is it the same housing i dont no if the housing had a posi unit in it before i got it.

can i make it a posi or do i have to get the right housing to hold the gears or is it the same housing i dont no if the housing had a posi unit in it before i got it.
Geez, YES, if you have enough money you can make it a posi. Buy a posi carrier to fit your housing and intended gear ratio, and have it installed.

The "posi" difference is in the carrier, NOT the housing. Which is the whole point of previous posters--it does not matter what was stamped into the housing forty years ago, it could have any or all of those original parts changed in the meantime. The ONLY reason someone would care about the original housing stampings is if they're looking for a "numbers-matching" axle for their show-car.

no iam not tring to make it a matching numbers show car i just want to know if it will be okay to put in say 3.31 to 3.73 gears and make it a posi with what i have already got thats all i wanted to know thanks for all the help with this.:hurray:

no iam not tring to make it a matching numbers show car i just want to know if it will be okay to put in say 3.31 to 3.73 gears and make it a posi with what i have already got thats all i wanted to know thanks for all the help with this.:hurray:
Why don't you take the rear cover off and have a look..What so hard about that? Like it's been said here already a lot can change in 40 years. Unless you have had it since birth. I'm starting to think you don't even own one. Are you looking at one on E-bay or one a friend has for sale? Are you overseas?

Don't make the mistake of ordering the wrong parts because you didn't take a look.

the cover is off and theres nothing inside it is empty.

Duh Duh . we knew there was nothing in side by the way you were talking . The gears werent turning

well........ with an EMPTY casting .... you can install anything you like .......

but you better PAY a pro to do it as you have non of the shim's to even have an idea where to start !!!!

be prepared to part with around 1500-2000 dollars depending on what parts you want it built with

and by the way i only paid 500.00 for it.:hurray:

and by the way i only paid 500.00 for it.:hurray:
For an empty housing?:confused:

I would have sold you a bare housing for 150

you have a 1966 chevelle 12 bolt housing for 150.00 where were you on friday.:mad:

you have a 1966 chevelle 12 bolt housing for 150.00 where were you on friday.:mad:
I didnt realize it was a short one. mines a 69 and not for sale anymore. sold my other today for 300. It was a complete 70 with pegleg 273s.

$500 for a D 16 6 dated houisng? If thats the correct date it would April 16, 1966. The casting number would not start with 3775.. ; but 3875... And the CF would mean that the housing was originaly assembled as 3:31 posi.

:hurray:I checked the numbers again and the 6 looks like a 8 but to me it looks like d-186 and then the housing has a n above the 3775---and the plug nut has a triangle piece of plastic covered with about 42 years of grease and dirt i cleaned up with some cleaner it says use positraction lubricant can anyone help with this thanks.:hurray:

UUhhgg!:sad:

:hurray:I checked the numbers again and the 6 looks like a 8 but to me it looks like d-186 and then the housing has a n above the 37775---and the plug nut has a triangle piece of plastic covered with about 42 years of grease and dirt i cleaned up with some cleaner it says use positraction lubricant can anyone help with this thanks.:hurray:

As said before... If you have an EMPTY case it doesn't matter what the numbers say. Put what you want into it! :clonk:

If you really paid $500 for an empty housing, take to a shop and have them build a posi rear end to the ratio of your choice. You'll be getting a sweet deal compared to what you've already spent.

Tom

D 18 6 is still a 66 housing; but there is no casting # for a chevelle that begins with 37775; should begin with 38775. Ever here of the Neenha WI? The Neenha Foundry made the castings for chevy 12 bolts. Hence the N. And yes $500 for a 66 housing is a good deal.

thank you for that i thought it was a good deal but the casting number has me puzzeled is there anybody out there that has seen a 12 bolt with the casting like that iam gone to take a picture so everyone can see what i have thanks again to every positive answer.

And yes $500 for a 66 housing is a good deal.


Oh really? Want to buy one of the 3 66-67 rears I have on the side of the garage? $500 for just the housing is a little high. $150-200 is a bit more reasonable. No way I would ever charge anyone $500 just for the housing. (unless they really deserved it!)

I'll buy all three for $200 each.

Got one guy coming to look tomorrow and two guys coming to look next week. Trust me they are barely worth $150 each in the condition they are in.

I got a freshly restored 12 bolt 66 rear with 3:73's and Eaton Posi I might part with for the right price! :D

Seriously, I have no clue why anyone would pay $500 for a old rusty rear with NO INTERNALS! Aftermarket parts are cheaper then that!

this is a short 1966 chevelle 12 bolt housing here not for 67 to 70 now it 53 1/4 from backing plate to backing plate a total of 60 inches.

i have a 12 bolt posi dated l 3 9 does that mean jan. 3 1969 or dec. 3 1969

Think that is "I" 3 9, which would mean Sept 03, 1969. The first symbol is usualy a letter.

so would that be a 70 rearend

Probably, is there a 3 letter code at the beginning of the assembly code on the front side of the pass axel tube?