The 163 signal replaced the 253 and 353 signals in the Lionel line up.
It has a single light showing. Compare this to the Lionel 253.
There are no variations of the 163 signal.
Note it would be easy to exchange the light hoods on a 353 and 163 signals to get base variations. The 253 and 353 always have black and tan bases, the 163 always has a plain tan base.