It has been a source of frustration to me that there hasn't been a good resin model of the RL MkII available in 1/76. Barry Wright had RLs in his extensive catalogue of white metal military vehicles until he retired a couple of years ago and his range is now being produced in part by Dartmoor models (on eBay) for the fire vehicles and by Matador models for the scout cars etc, some of which have been recast in resin, though not the RL as yet.
Some of you may have visited Frank Waller's 'Road Transport Images' stand at Scale Modelworld Telford last November: Frank has just sent out his latest newsletter and he now has the MkII RL in his range!! Note you have to buy the cab, chassis, body and wheels separately and the combination isn't cheap but it's lovely!
If it's a Mk1 you're after you're in luck as Frank's had this available for a while though be quick as he will archive the Mk1 cab shortly.
Currently if you visit the website you'll only find the Mk1 cab available but I'm sure Frank will update the site shortly. If you've not visited before see also his other military models including a couple of 'complete vehicles'.
BTW I've no connection with Frank or with RTI other than having met him and ordered some of his, mostly civilian, models in the past.