If there is an enclosure sold for that unusual, but once common, hard drive, I don't know where you would find it.
You apparently have one of the very good, but unusually sized hard drives from the 90's that was found in several Gateway, HP, and Compaq computers... They came in various sizes from 3 GB to 12 GB to 20 GB... They will connect fine, but there is no enclosure.
You may need a tech's help, or some body experienced in saving data so you do not damage or lose what you have.
You need, temporarily, an IDE or EIDE computer... not one with a SATA drive...
But you can also use that drive WITHOUT the Enclosure... just the connector if you have total control of your working space.
I can send you a photo, but describing it is cumbersome.
Some enclosured require you to mount the drive (3.5 inches) in the enclose. Some do not.
One end has a power socket and a USB port with a small circuit board that is 4 inches wide and 2 inches long... with power cable and EIDE cable.
This will fit nicely on your hard drive, but it may be difficult for you to know how to do it unless you have experience putting your hands inside the case.
The device costs $27 to $40 depending on where you buy it.
one power cable goes to the power socket on the hard drive. The other cable, an EIDE 80 conductor, 40 connector cable connects to the computer business end of your hard drive.
Then you would place it on a non-conductive surface on a table or desk that will not be used for anything else until you are done.
Once it is connected, you plug the USB cable into the old drive contraption above and the other end into the computer in which the data will be moved.
The device has a power adapter that looks like the adapter to a laptop. It plugs into the wall on one end, and into the contraption on the other end.
With the power switch on, the hard drive acts like any other "Slave" drive, and you drag and drop or search or whatevefr from the computer... moving the data to the new computer.
You need to know something about how the file structure works.
If you are copying the address book, you need to know what software created the address book, and what email software created or saved the email files.
It is complicated to describe, but easily done.
I will be happy to send you a photograph onf one setup, and discover the brand name of the one that will work best for you, or even do it for you without charge.
It will be helpful for you to make several notes about what some of the file names might be, and what software created them.
It will not copy the programs in a workable format. You will still need to reinstall the software to from the original source in order to run the programs... but word, excel, powerpoint, photographs, images, Quickbooks, and other programs will read these files as they would any other.
We are open to questions if we are not clear enough.