The 9 1/4 sure grip diff. in '94 -up pick-ups and vans are not real uncommon i'd guess 35 or 40 %. (which is quit a few).
I have meant to research if it is possible to use the later model truck diff. insides in a '70s 9 1/4, just haven't sat down to do it yet. If in fact the parts are interchangeable (carrier, gear set, axles, etc.) It should be a fairly cheep way to get a sure grip set up.
On a side note most later model 9 1/4's have 3.50 gears. :3gears: