Initially, I had the same problem when I replaced the differential. What worked for me was to tilt the differential, on the jack, where the mount studs all entered the subframe at the same time.

It would not work, with any amount of prying, to start two at a time and try to lift it in place. The spacing of the mount holes is just too tight for this, as you are finding out.

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Sam

84 300SD 350K+ miles ( Blue Belle )