How many Mechadendrites can a TP have? I looked through the rulebook and this forum and have been unable to find it. Any help is appreciated.

Nodens said:

They can have up to their toughness bonus worth of mechadendrite.

It is indeed Toughness Bonus as a maximum number of mechadendrites. Machinator array helps with this.

I believe the number is resolved in the errata (found on the support page).