Nah mate, I have seen a few, You just need to be patient, and one will pop up, and ALWAYS keep a good eye on Tiny's green shed, he gets some great ones in there.
My MKI (the one with this on it) came from there, as well as 2 rare green-top auto drives, a nice 1973 Rover pedigree, a power plus self propelled, and countless VC's, as well as pleanty of other rare or uncommon machines.
Sure the things you get there need some work, but it's worth it with all the rare ones he gets.