Central locking slave - options for a small space

[YBOD]

I am looking to fit a central locking slave to the rear door on my canopy. I thought this was going the be an easy job of simply adding a Jaycar slave like this one:

http://www.jaycar.com.au/productView.asp?ID=LR8813

However I've struck upon a problem. The cavity behind the lock assembly is too small for the Jaycar model, in particular the cylinder about halfway along. Anybody know of a smaller or at least narrower slave unit. The cavity in the door is 40mm x 50mm.

Cheers

 

[KraftyPg]

Just search Fleabay, there is a range of actuators of varying prices many of them look like they came out of the same factory but if they don't have the measurements ask the seller.