Beg to differ with you. I have replaced several low mileage boxes that leaked with Cardone rebuilts and have never had a problem with them. There were three steering boxes from, I believe 1966 through 1976. 1 for the Eldorado with one tuurning ratio, a swcond for ALL standard cars, and a thrid for the Commercial chassis/Limos.
The commercial box steers slower and the Eldo box steers fastest. The problem with the rebguilders is that you never know what ratio you are going to get. What I have done is order the box and when it comes check the ratio by comparing the input turns to the output turns. The only box I have turned down was a commercial box, but when I returned it the next one was correct.
By the way, I do believe that a whole bunch of other cars used the same box for a number of years.
Greg