I hope for the first time ever, and thanks to Mr Clive Law for finding the papers, I am able to post a breakdown of the 1940 CMD assembly figures. I suspect that the 30-cwt ambulances were F30S, with Mann Egerton bodies...37 were ordered in the first tranche of contracts. The photo in Dr Gregg's book showing delivery of CMPs has what I believe is a F30S ambulance, judging by what I could see of the front radiator gyard spring leafs, but those with sharper eyes may say it's a Chevrolet. The others seem to be Chevrolets.
1940 CMD production breakdown