There is a lot of confusion in this thread.
Brad is correct of course, there were two 1/24 scale sets as he described.
Now...
Am I right in thinking thatn the RTR cars are Homeset ones?
It all depends, since they could be used at home or at a commercial raceway where they were also sold. The "set' cars of course had different chassis from the "kit" models, but there is no such distinction for the 1/24 scale vacuum formed cars, in which at least one of them was sold in kit form, and that one is by far the rarest Monogram kit of them all, with so far only one known to have survived.
Also I might be mistaken but was not the Indy Lotus (Lotus 38) produced with a plain undecaled body in Green and Blue for the Homset RTR version?
This is incorrect. The Lotuses used in the racing set always had self-adhesive poor-quality decals that often are missing from their bodies. These Lotuses used narrower rear wheels and tires than the version sold as a kit, and were fitted with only a small portion of the plated cosmetic accessories supplied in the kits.
Now Phillipe the $64000 question were the bodykits for the Ford GT and the Ferrari 330P/LM every issued as seperate items?
No. They were sold only as full kits or fully assembled RTR models, inside small clear plastic boxes. In fact, there are more Monogram models of which the body kits were never offered separately: besides the two you mention, the 1/32 scale Lola T70, Ferrari and Lotus F1 (although these two were offered as static kits but using different parts), as well as the 1/24 scale McLaren-Elva, Lotus 38 and all the vacuum formed cars, from Vampire to McLaren-Elva.
And indeed the whole detail of this will be described in great detail, year per year, in the new book due in 2010. A listing of everything (kits and RTR) ever produced is located at the end of the book, with stock numbers.