What are these on 1998 Diplomat

[uksteve]

Could anyone tell me what these are please
Next to air tanks

[CountryB]

Are those electrical wires going into the valve?
It's hard to tell from the photo - how many air lines are connected to it?

If it is screwed directly into the ir tank, then maybe an automatic tank water drain with heater (like this style) https://www.anythingtruck.com/product/061-284412X.html

Or if air lines go to brakes and there are multiple valves, maybe part of the ABS system (if you have antilock braking).

Perhaps you can post some more photos of the valve from different angles.
Good luck.

[uksteve]

I think it’s just air lines going into it