Hi I'm looking for help on i2c multiplexer where can I purchase one. what type /part number / preferably DIP ?

this is for use with multiple i2c with same address not i/o expansion

thanks in advance

Hi, welcome to the forum.

Which i2c chip is it ? is it 3.3V or 5V ?
You can make your own by muxing the SDA with a 74HC4051, or a special chip like the TCA9548A or dsscircuits.com is for sale | HugeDomains.
It is even possible to use SoftwareI2C.