Hi Jimbob, the 8 wheeler Atki's are, or were, called Defenders and the length would depend on what it was used for as a tanker would be shorter than a flat..... Sorry, but off the top of my head I don't know the length although I would be able to obtain a body length for a Holt Lane Transport Defender which would be similar?.............

The maximum vehicle length for an 8 wheeler of the period the Defender covers was 36' 1", so using that as a measure (you can drop the inch!) you can work out your body length, also to bare in mind was the Max Gross Weight which for an 8 Legger was 28Ton but this could only be achieved if the outer axle spread was 23ft, so basically to carry the heavier weight it had to be on a longer body. I would presume if Suttons ran some of their 8 wheelers solo they would go for the longer bodies but if they were pulling trailers this would restrict the body length as the Max length of a wagon and drag was 59ft and as the trailers were around 23ft Max(not including drawbar)this would mean a shorter prime mover.

All sounds a bit complicated which it actually was and typical of British transport laws. I don't know if you are copying from a photo or not but I would say as most body lengths were anything from 24 to 30ft with the odd exception you pretty much have a choice of wheelbase, as infact Atkinson had various lengths offered, if you use the 23ft outer axle spread as a guide (11.5" in 1/24 scale) this being the maximum and keep within those dimensions your chassis will turn out okay. I have always prefered the short wheelbase 8 wheelers myself for a nice compact look. Past copies of TMW have the Atkinson in 8 wheel guise. Nos.