There are application forms available off the DVLA website:
http://www.dvla.gov.uk and also your local registration office..I don't know where it is in Kent. To confirm age of truck I can assist as I have done this with Chevrolets in the past. Theoretically you should have a 1945-50 rego as that's when such trucks were demobbed and registered [more or less]. That's therefore before the XXX VSU reversal of the plates.