I have read so much, my eyes went crazy !!! lol Seriously though, I am doing a drum to disc conversion on the rear of my 70. I would like to know what, if anything, I should inspect, or replace, inside the 12 bolt rearend. ie, bearings, seals, gears, etc. Any comment or suggestions, as always, will be greatly appreciated.

If the rear end is in good condition there should be no need to replace anything if you are just swapping brakes. If you remove the axles and find that they are worn where the bearings run on them then you will need to replace the axles and axle bearings.

I'm about to perform the same thing on my 66 Chevelle SS - it's has a 12-bolt rear end and removed form the car at the moment since I'm doing a frame off. I've never performed a drum to disc swap before and I'm about to order the full disc brake conversion kit.

What will I need to do the the rear end in order to get the old drums off and the new discs on?

Thanks,

You will need to remove the axles to get the backing plates off. Raise the car and remove the wheels and brake drums. To remove the axles you must remove the cover, which will drain the oil. Then remove the retaining bolt that holds the cross shaft in place. Remove the cross shaft and push the axles in so that the c clips can be removed. Don't turn any of the gears (4)inside the differental while the shaft is removed or you will find them laying in the bottom of the housing. With the c clips off you can pull the axles out of the rear end and swap the brakes. Check the axles for wear where the bearings run on them. If the axles are pitted or worn then they should be replaced along with the bearings. Install the axles and put the c clips back in place. Put the cross shaft back in place and install the retaining bolt with blue Lock Tight on the threads and torque it to 25 foot pounds. Put the cover back on and fill it with 80W90 gear oil (about 2 quarts). If it is a posi then don't forget to use the bottle of GM or Ford limited slip oil additive.

Excellent step-by-step. Many thanks!

Are you using a kit, or swapping on parts from a factory application? I used the setup off of an '80 Trans Am on my Firebird, and had to clearance the flanges on the axles for the disc hat to sit flush. Since the car has a posi, I started it, put it in gear, and used a grinder to turn down the flange's outer diameter. Stop and test fit a few times until it's good. If you do have to do this, remember to shut off the engine before trying to stick the trans into park, since you don't have brakes to stop the axles. ;)

I'll be buying a drum to disc kit.