Regarding your quest for an e-brake, from what I see from your photo of the differential (taken looking upward) it looks like you have a "disc" on the pinion U-joint yoke. My e-brake system is similar, so try searching for an "Airhart" e-brake. It includes a cable actuated caliper that grasps that disc attached to the differential yoke. Wish I could attach a photo, but the car is about 860 miles from my current location...but I will be down in that vicinity for Father's Day, so maybe...?
Cheers!
Dugly
