I just put a measure on the yellow one that I have, it's 145mm wide!
A hefty beast for sure, I bought mine a couple of years back when GRS were clearing out a stack of them - paid £100 at the time, pretty much the same price that other shops are currently doing it for.
To be honest it was an impulse buy, I'd always been planning to chip it but never got round to it, it's actually never been on the track (I'd not even got round to swapping the knuckle couplers for the LGB-type ones) - if anyone wants one, I'd be open to reasonably sensible offers for it! It's in unlettered black and yellow.