Brake drum identification

OK guys. Here's my problem. I need to replace a brake drum that I am having trouble identifying. It is on a 1956 Chevy ten bolt rear end, but according to GM the replacement is different than what I have. It's an 11 inch drum with a 2.5" shoe surface. The lug pattern is 5 on 4.5 with holes for 7/16" studs. The actual shoes are 1.75 wide. There is a casting # on the drum that reads 212004-C. Is there anyone out there that knows what I have? Any help would be greatly appreciated. I have been trying to figure this out for almost 2 weeks.

 

If the bolt pattern is 5 on 4.5, it ain't a '56 Chevy
reearend! Someone's probably swapped it out for
a Ford or maybe a Mopar rear. Can you post a pic
of the rearend so we can I.D it?

Mart3406
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By "ten bolt" do you mean the bolts that hold the rear cover on, or the bolts that hold the pumpkin in?

 

The stock shoe for a '56 is 11 X 1 3/4". My old Delco book shows the drum as 2" wide.
Remeasure the bolt pattern. I'll bet it is 5 on 4 3/4".

 

I know that it is a Chevy from the GM casting #'s on it. I used those #'s to do some on line research and that's how I found it fits '56 passenger cars and corvette. As far as a photo, I can't do that untill Wednesday, so I am just trying to make do. Model A vette you are exactly right. I was measuring the studs wrong (center to center). They are 5 on 4 3/4.

 

Model A Vette I still have one more issue. The Delco book says it is 2" wide, but it measures 2 1/2". I don't know if it will help, but the center hole measures 2 3/4" and it also says maximum diameter 11.06 on the outside face.

 

The Delco book doesn't give any more info than what I gave you.
"11.06" Max over size was standard at the time allowing the drum to be ground .060 oversize before it was to be discarded.
I would not worry about the 2 1/2" measurement you come up with as long as the drum doesn't rub on the backing plate and seats on the axle flange.
Are you measuring where the shoe rides or the overall width of the drum?

 

I measured the overall width of the drum. My shoes do measure 1 3/4".

 

The 2" measurment that is listed in the Delco book refers to the surface where the shoe rides.

 

By the casting number that is the correct drum, and it was made in the USA. Offshore drums don't have the casting number.

 

No offence, but are you sure you are measuring the bolt pattern correctly on the 5 on 4.5". If you are measuring 4.5" bolt center to bolt center,,,, that is a 4.75 pattern.