2 sets of bi-directional inputs and 1 output across 2 different voltages

So there is a chip I'm wanting fabricated that will be plugged into using edge connectors / gold fingers 2 completely different systems.

One system is 3.3v CMOS and it has one set of pinouts.

The other system is 5v TTL and it has a completely different set of required pinouts.

All I'm wanting is for one of the 2 sets of pinouts to be connected to the edge pins allowing for bi-directional traffic

When looking at multiplexers, assuming multiplexers are my solution, the problems I'm running into is

  • voltage differences
  • CMOS/TTL differences

While I'm wanting just a wire connecting the pins to one of two wires it instead determines on it's on whether it's a high or low based off of either CMOS or TTL and then gives the correct output which isn't what I want because one system will use CMOS and the other TTL and the multiplexer only goes off one system so I need it to just pipe the wire through.

Maybe theres another solution and multiplexers aren't it or maybe I need to do this with passive components and skip IC's. I'm not sure what to do but any help would be great.

It looks like this might do

https://www.mouser.com/datasheet/2/464/IDT_QS3390_DST_20141013-1486859.pdf

But I'm still confused (From looking at the electrical specs and ratings) if it can handle and pass-through 3.3v and 5v data signals of CMOS and TTL.

So I'm still at a loss.

Is there any overlap in the used pins? Or are pins in system A, used for something else in system B?

Otherwise I would just use different pins for both and add a bidirectional level shifter for the system with the different voltage than your uC.

Unfortunately their totally different usages and purposes - I would want them to be isolated completely behind a switch.

I'm using resistor dividers to divide the voltage down to 3.3 from 5v but it still doesn't help with the TTL and CMOS specs.

Luckily TTL and CMOS isn't much of a problem with the uC and other components but it seems to be a problem with the multiplexers as the high and low are not aligning properly. The multiplexer data sheet is confusing because while it acts like there is a high and low voltage range it also says the 2 ends are directly connected and gives a general voltage range so I'm pretty confused as to whether it matters or not especially if the wires are directly connected.

I'm not sure if I should pursue the multiplexer solution but it seems like it's the best solution I've found and the one I posted earlier seems like a good one to use it's just the datasheet is confusing a bit as to whether it will work or not.