Sorry mate, I don't know how to answer your question but wanted to put in my 2 cents...
I looked at buying an engel a while ago and ended up buying a Bushman fridge instead.
It has digital control, uses an average of 16ah per day and comes with varying configurations of lids & collars for around the $1200 mark.
I don't sell them or have any affilitation, nor could I tell you where to get one in WA but in my experience, I found them to be a great product.
I believe it uses a similar danforth compressor to what the Engels used and are Australian Owned.
They also have better insulation properties but this means they are a little bulkier than the Engel.
I havent had anything break on it yet after a year of 4x4 use so can't tell you about their warranty or service.
I would check them out if I were buying again, and you may still end up buying Engel as it is a good brand and a good fridge, but it is good to know what else is out there....
bushman.com.au/