I have an old jacuzzi shower/tub with a Fredrich Grome valve ( no knobs) that was leaking. First, it was just if you tried to turn shower on, now it’s tub or shower. The second observation I noticed in service areas was that the port on top of valve or opposite the tub supply line and I guess traditionally is used for shower is capped off. The third thing a “twin ells” in there service area that a ¾ inch tub spout connects too and supply’s tub with water as well as shower.

So my question is what type of valve do I buy. Should I just replace valve and reuse spout or might those parts in spout be ready to go soon too and should I just replace that too. Would I need the twin Ells if tub spout connection was ½” opposed to existing ¾. Pictures can be provided for further clarification if needed.

I assume you meant Friedrich Grohe, if so this is one of the best valves made. I would look at repairing it rather than replacing it. Where is it leaking from? Pictures might help.