I think this is an S trap - kitchen sink from the 50's

I'm thinking this is an S trap?
If the last 90 was a T fitting with a vent going up it would be OK?
Kitchen will be remodeled in the future, maybe 2 years away. Unfortunately where the wife wants the sink is 7' further away from the main vent pipe (Cast). At the new location I will be able to go up into a 2x6 wall & then over to the vent pipe - I think. Possibly rip the rest of the cast out & replace with PVC

Yep, that's an S-trap...To change it, you need a vent coming off instead of the elbow.

Thanks, doesn't make sense to add a vent right now
But if the wife can verify the new sink location that will make it easier to start figuring out the route for the new vent pipe

*shudders at the thought of saying this*

Umm well .. heck I will just say it. Why not put a studer vent in for now. Something is better than nothing.

*runs and hides under the bed*

Yeah, I thought of that
But it's been this way for 50 years
The plumbing is a bit "delicate" shall we say
Notice the wood block holding up the drain !!
I don't want to touch it until I have to