The Stovebolt Site Forums The Parking Lot Big Bolts Identify this rear end and ratios

This was offered to me. It's a 2-speed rearend, but may not be original to the '64 C60 it currently resides in. Didn't think to measure the brake drum width before I left. Can anyone ID this rear end and/or tell me what ratio might be in it?

Numbers on the pinion support:
http://i683.photobucket.com/albums/vv198/aaa-111/trucks/Goliath/2011-10-07175506.jpg

Horrible shot of the back of the axle:
http://i683.photobucket.com/albums/vv198/aaa-111/trucks/Goliath/2011-10-07175358.jpg

Front of the axle and the vacuum actuator for the 2-speed:
http://i683.photobucket.com/albums/vv198/aaa-111/trucks/Goliath/2011-10-07175512.jpg

It is probably GM because I think they are the only ones that used vacuum shift. It could very well be original in a 64 60 series.

Here's my guess if the differential wasn't changed out over the years.

If it has 15x4 brakes (15K axle) it could be a 6:40/8.72 or a 5.83/7.95.

With 15x6 brakes (17K axle) it could be a 6.40/8.72.

These were the popular two speed axles during the mid sixties on GM medium duty trucks.

SimS

Thanks SimS. I saw that data on this site someone else linked me to. That's why I noted that I forgot to look at the drums.
http://www.chevyc60.com/the_rear_axle_page.htm

I thought the numbers on the pinion support were supposed to be the pinion and ring tooth count, but I don't know how that would work with the additional gearing in the rearend.

I also thought that the 2-speeds were all Eatons. Was I wrong? Are they Corporate? Either way, is there a model number for the axle so I can refer to it somewhat intelligently when looking for parts?

If I had to guess, I would say Corporate. Take a look at this OldCarManualProject web page:

http://chevy.oldcarmanualproject.com/booklets/55top18/5518sm01.html

It looks a lot like your beast.

SimS