Thanks for the replies.
I'm a believer in the Scorpions. My Yuasa lasted only a year too, but this Scorpion is so strong it fires in under a second on my z1000 - and thats a bit of motor to get going. It just has the kind of current where you hit the button and you hear no struggling from the starter motor. I'll try and remember to post back next year on how it works in the Tbird.