installing a ext.hard drive to a new iMac

Exactly what FireWire external drive do you have?

(many had both FireWire and USB connections on the back)

Yes you can get and use a couple of expensive adapters to go from Thunderbolt 3/USB-C to FireWire.

https://www.apple.com/shop/product/MMEL2AM/A/thunderbolt-3-usb-c-to-thunderbolt-2-adapter

https://www.apple.com/shop/product/MD464LL/A/apple-thunderbolt-to-firewire-adapter

However IMHO, you would be better off spending your money on a newer external drive to replace that old FireWire drive.

John, not really the USB-C Thunderbolt ports are faster but you will only notice this if you are constantly moving files from internal to external and are using a fast SSD. I'm on a 2020 iMac and from what I can determine the transfer rate seems limited more by the HD speed than the port speed.

I hope this helps.

Paul

John, I was thinking space wise 1TB? or another size. I debated on how to ask the question. I figured you would respond as you did because I don't always ask questions in manner that is understandable or can be interpreted in multiple ways.

You should be able to plug the drive in with the cable that came with the drive to the USB A ports on your mac.

Paul

No. If you already have the EHD, any port of the same kind is equivalent.

What G-Tech model do you have...?

(most of them also have USB that you can use)

Yes that will work. In fact, it should have originally came with USB, FireWire and eSATA cables.

Yes, the USB 2.0 will work. It will be much slower than than Firewire. USB 3.0 would be better. How large is the drive space wise?

Also which iMac do you have.