Hi hj308 welcome to the forums, I hope you had a good look through the website especially the detailed identification page www.mysandman.com.au/ident.html. The Sandman must have full headlining, it was one of the key features or sales points of the model. Without the headlining strip I'm pretty sure you have either a HJ with owner added GTS options, or dealer ordered GTS options.

Instead of the 253, the codes tell me you should have a 308 plus 4 speed manual. Would be great to see some photos if/when you get a chance.

Try and get the Body Plate details too, that would be handy.