We have a lot of older equipment we keep operating from plant to plant and also do some non conflict repairs on equipment that uses this 747 Op-amp. It has always been a problem locating these chips and some times end up using a NTE replacement, which I really don't like to do because it's a crap shoot at times.
I went on line the other day to locate some of these babies and I couldn't believe what I saw, Newark had over 1500 in stock of the UA types! The ones we have are LM but who cares, if they work its fine.. So I ordered 100 just to make sure, the price was right!
P.S. It appears these LM747 are very destructive just from a slight over voltage on the inputs. It not only destroys the Op-amp, which would be expected but it also splits it in pieces if you don't have some sort of current limit on the Vcc.. ;)
Jamie