Thinking logically, I'm assuming the 335/351/359 tender might be something like this:

351 - Newcastle to Whitley Bay
359 - Killingworth to Whitley Bay (via Murton)
335 - Killingworth to Hadrian Park.

From my maths, this could be done with 5 buses. I don't really see any need for the section beyond Hadrian Park on the 335 if 359 can serve Murton.