Phil,
That's not right. That's the service schedule for a Boing 737.
My Mk 2 GS service book says
A/B services at 9,000/27,000 miles
replace air & fuel filters on B-service
replace plugs and timing belt at 63,000 miles
replace ATF every 36,000 miles.
It's the plug change that is a real sod. Much worse than getting to the timing belt.
My GS is a mid-98. I wonder if your is later and they have changed the schedule. My cambelt came out like new at 63,000 but 150,000 is a bit chancy!