Transistor question

[droptop]

Moderator- if this is in the wrong forum please move. Not having much background in solid state servicing finds me in this situation: I'm restoring a 1965 Sony videocorder. In searching for replacement transistors I’m not familiar with the meaning of the digit after the dash in the part numbers. Is this last number significant from a rating standpoint or can it be ignored? These transistors are used in the servo control circuit. What follows are the Sony transistor part numbers in question.

2SC401-4
2SC401-6
2SC318-16
2SC299-4

An example is the 2SC401-6. Using 2SC401 without the 6 indicates 2N3710 as a sub using an online cross reference guide. Subs were found for the others by using the part numbers without the last digit(s).

A 2SC4016 transistor exists. Could this be the same as 2SC401-6 with the dash omitted as in an updated numbering system?

Thank you very much, Rick