Peter Jones has sent through a couple of interesting files on the early RL24. There is a price list from 1986 and an extract from Cruising Helmsman with an RL profile summary from 1987.
Both of these can be downloaded from the RL 24 page.
Jeez, I'm tipping the scales at just over a ton for a mk 4. I know that I have 50kg of battery in the boat but where is the big weight difference coming from.