Are they from a specific series or something? A lot of models are still around, but something like RCA's SK series replacement parts usually are listed in reverse - they were marketed as replacements for a variety of amps, so you'd be better off looking up the part and finding what they would replace.
Otherwise, if you have a datasheet for the original, you can probably get a close match for gain bandwidth product, input bias current, voltage range, slew rate, etc. and get something pretty close or better specified than the original. Maybe what they're used for is a better place to start? A lot of opamp uses don't really demand any particular replacement, but higher bandwidth, high sensitivity frontends, low distortion requirements, etc. could push you towards a good general replacement for the application.