I would assume that the T670 would be wider than a STS? Our 9870s have a substantially heavier feeder chain than our old 9860s, we have the aggressive feeding package so I don't know if that makes any difference.
John Deere has changed the feeder conveyor chain several time throughout the 60 series. The later ones are the stronger. The length has also been changed especially with the latest feeder house front plate in 2007. But lenght can easily be changed to adapt.
The chain life can be increased considerably by keeping it adjusted right all the time. I have seen many chains not maintained and therefore wore out quickly, by overstretching the center chain.
Thanks for the reply JD Im sure the feeders are the same basically, but havent seen proof that the T series has better chain, the weight of a heavier side plate chain may be bad for sprockets too I suppose. Ive got a guy checking into some other options too, there is a 555 roller chain with the same pitch too but not sure about the roller diameter,,,, any way thanks.