I also wondered about that but all 6 plugs are clean and appear to be in the right heat range.
I use AC R45S and replaced them about a year ago, last time.
If I go down one size on the carb jets I get hesitation when accelerating.
It's possible that these engines warm up a little sooner in the rear.
But I have never noticed signs of uneven cylinder temps when fully warmed up - driving it every day since the mid 90s.
I like learning and listening and sometimes take a more experienced person's advice as gospel and go with it for a while until I can confirm or dismiss it.
Glad I asked around while it all was just a thought.
Thanks for all the helpful advice, as always...
