@Mackers Seriously, mate it's obviously very important to give an accurate description of your vehicle otherwise it makes it very difficult for folk to help you out. This forum is awesome. However, the problem with any forum is that the communication is via typed posts. This is not as fast or efficient as talking face to face, where clarity can be achieved far more easily. Post a picture of the engine and we'll be able to tell you what it is. The age of the vehicle will narrow down the original spec. The VIN number off your V5 tells you exactly the original spec. To be super safe, don't post your VIN number on the open forum. However, you could send it via a personal message to one of us. (white envelope symbol top right of Landy Zone page and it's called a Conversation.
As has already been said you should be able to fit these
LINKY TO STEP
View attachment 162259
This is the standard type step fitted on Defenders. Although my originals had a support bar that went across to the main chassis rail. I've got long side steps, similar to the ones in your picture, fitted now.
I think we're all wondering how you can't fit steps!
Why don't you post a picture of your fuel tank and we can see if it's standard or not?