I'm replacing the axle seals on my truck. The passenger side seal let go and leaked into the drum. I believe the axle is supposed to have a vent on it somewhere, but I can't find one. I also find no identifying marks on the differential or anywhere else aside from 3 hash marks. At some point someone installed a 3-speed Saginaw transmission, so I don't know what else was done to it and I'm wondering if the driveshaft and rear end are original. I'm new to stovebolts, by the way.
Anyway, here are some pictures of the differential, rear axle, and u-joints. I was hoping someone could tell me where the vent might be located and if any of this setup is other than original. Thanks.

[IMG]http://i7.photobucket.com/albums/y261/bohon/56%20Chevy%20truck/RearAxle062.jpg[/IMG]

[IMG]http://i7.photobucket.com/albums/y261/bohon/56%20Chevy%20truck/RearAxle063.jpg[/IMG]

[IMG]http://i7.photobucket.com/albums/y261/bohon/56%20Chevy%20truck/RearAxle066.jpg[/IMG]

[IMG]http://i7.photobucket.com/albums/y261/bohon/56%20Chevy%20truck/RearAxle067.jpg[/IMG]

[IMG]http://i7.photobucket.com/albums/y261/bohon/56%20Chevy%20truck/RearAxle069.jpg[/IMG]

1956 Chevy 3200