Don't know of any RME receiver with an eye tube. The 70 year old cabinet doesn't seem to have any blemishes on it so most likely has been repainted. The hole for the eye tube is also not centered properly and there is no outer protective ring mounted in the hole for the tube. RME also offered an external S- meter for the model 84 so an eye tube makes no sense.
Is this the receiver:
Doesn't look like the best "buy for the buck" receiver. Single conversion, mostly 7 volt tubes, no filter, sold for $98 new, But wait - it has an internal speaker.