Delco starters were used on many things other than Chevs.

Best source of grimy = minty caps here is Larson implement in Cambridge MN.
Shelves full of solenoids- starters.
Many of my tractors have the right cap.

Remember the metal solenoid body is dated and numbered.

Just checked epay searching "NOS DELCO STARTER SOLENOID".
Plenty as usual.

I am not the final answer on this so look hard and closely.

Remember you n4ed the notch on, top for cable locating ear.
They do not all have that.