I recently had a search done on my Humber Pig, which was released from service in 1967, and Croc had a search done at the same time on his Scammell Explorer which was released about 1970ish
In both cases RLC Deepcut did not have the records, apparently prior to 1970, the B Vehicle cards were not kept on vehicles being cast, or certainly very patchy, anything after that point stands a better chance of being found.
Also for the short arms, deep pocket types, if you have more than one search it is £15.00 for each vehicle search after the initial £25.00 fee, so if you know anybody else who would like to find their vehicle history, get together and save a few quid, its less disappointing when you get bugger all back!!