Thanks, guys! I appreciate the positive feedback. I hope that people will find my build to be informative and inspirational.
I am still preparing to install the engine and transmission. I had planned to install them Tuesday while my son was off of work, but found out that one of the engine mounts was incorrect. The box had the wrong part number in it. So that is being replaced by Amazon. I have the parts staged and ready to go.
I am also working on the fuel system getting ready to install a new fuel tank. I will post photos of that soon. I am also planning to do posts on the transmission and engine that were previously completed.
I thought I would talk about the 12 bolt while waiting. My El Camino had a 1967 12 bolt in it when I bought it. The original owner told me that during the first year he owned it that the posi didn't seem to be working, or didn't have a posi. He told me that the dealer swapped the the posi rear end out of a new 67 El Camino. So he said, and the rearend that was there was a 1967 with a 939 casting and a CF code indicating 3.31 posi. The Protect-O-Plate indicated that my El Camino originally came from the factory with a CF coded rearend, which would be a 3.31 ratio with positraction. I found that a previous owner had changed the gears to 3.55.
I wanted a 66 rear end in this truck so I sold the 67 rear housing after stripping it of everything but the bearing retainers. An empty housing can be shipped Fedex, under a 100 lbs.
I found a 66 rear end being advertised here on Team Chevelle. The owner, in Salt Lake City advertised it for $200, must pickup, won't ship. I sent him a message offering an extra $100, plus cost of shipping if he would strip it down and ship it to me Fedex. I soon had my housing. The housing was very nice except for holes that had been drilled in the shock supports to relocate the shocks for that day 2 jacked up look. These holes were easy to re-weld. The housing was actually a few months too early for my car and did not have a CF code, like my original. It had a CW code, 3.31 open, that was the standard rear in a SS396. But I had kept the posi out of the 67 housing and it would fit in this 66 housing. The 1966 housing casting number ended in 745 and had flat spring perches. So this rear end would look fine under my El Camino. This being an early 66 housing, with an August casting date and a September assembly date, it had only one hole in each spring perch. Later 66 housings, have 2 holes in perch. Not sure why the extra hole was added, my guess it that it was for spring alignment purposes.
I sandblasted this housing several years ago and painted it cast iron gray. The factory painted the completed rear ends black, but I like contrast, and was modifying the car anyway. A month or so ago I rebuilt the rear end. I bought a new installation kit, yoke, axles, solid spacer, and an Eaton service kit with steel discs and shims for the posi.
I rebuilt the posi with the Eaton kit, part number ETN-29403-00S from Summit. This kit includes the shims needed for tuning it per the Tom's Differential video. A link can be found on the differential forum. I re-installed the original 200 lb springs, since this will be a street car, but were unnecessary when tuned per the instructions from Tom's video.
I installed a solid spacer in the pinion rather than use a crush sleeve. The solid spacer comes with shims that allow the pinion pre-load to be adjusted and then the pinion needs to be torqued to 125 ft lbs, per the instructions. Others recommend up to 200 lbs of torque with a solid spacer. It takes a few iterations to get the right set-up, but once done you remove and replace the pinion to replace pinion shims or seals, and just re-torque when done. And you don't have to crush a sleeve.
I posted photos of my gear pattern on the differential form. Members were very helpful in interpreting the patters and suggesting changes in pinion shim and backlash. I couldn't have completed this rebuild myself without the help of these TC members. Thank you! Here is a link to those posts and quick photo for those that don't want to check out the post.
I finished the final installation of the pinion seal, yoke, and final torquing of the yoke. I needed to install the Camaro brake backing plates before installing the axles. Axle endplay needs to be checked, before installed and sealing the rear cover. If you have any reason to remove the axles later, wait to seal the cover. Here are some photos of my completed 12 bolt.
The correct positraction tag says 'positraction" rather than 'limited slip" and uses a filler plug that has a lip to retain the tag. The non-posi filler plug did not have the lip. This CW coded housing would not have a tag and special plug, but I added them to this housing because I added the posi and want the rear to look as if it was original to my El Camino which did have posi and the tag.