Land Rover 3.5 V8 carb balancer (tool code 605330)

I am on the market for the carburettor balancer (special tool code : 605330) mentioned in Land Rovers 110 Workshop Manual (1983-1992) but cannot seem to find it. I would greatly appreciate it if anyone could supply the tool or share some info on how to adjust the twin zenith carbs (CD175SE) with a common carb balancer. (e.g. carb sync)

I balance carbs/throttle bodies on a fairly regular basis on motorbikes.. i use my own home made tool for the job that cost about £5 to make and works perfectly. Doesn't look professional though