...I had it out this weelend and it wouldn't flex enough to make it up simple looking obstacles. Would a rear locker make much of a difference in these situations. Basically it will flex a little lift a tire and sit and spin.
BTW Thanks for the info.
Yup, I bought my 79 with open diffs and in one evening put in 4.7's in the t-case and welded the rear and it made an amazing difference for what I could climb. Completely stock except for t-case.