I already had some thin brass strip which cuts easily with sturdy scissors, so I planned the shape and cut them from the strip. This tends to curl the brass a bit, so I flattened them both out and one at a time, superglued them into position on the chassis. Just for good measure and as a precaution against them becoming detached at a later date, I drilled a couple of 1/16 holes in either end. I then lightly countersunk the holes on either side. Last step was to fill the holes carefully with more superglue. These, I hope, will act like little rivets and help keep the strips in place. Another plus is that the shortened front lead wires act like reins and keep the guide facing forward for marshalling moments! The final test was to refit the body . Saints preserve us!! The body now drops on in seconds flat and the trauma of fitting Mr Fly's bodies at a critical moment in a race evening are gone forever. Well Mr Fly(slot), at the price you are currently charging for your models, I'm sure it wouldn't be too much problem to add this or something like it to some of your more difficult models???
(n.b. the gold spray on the chassis is paint which it contracted in a former incarnation)