There is no difference besides ratio. Any bravo x or XR can go behind a gas engine. They all work and perform the same no matter the stickers or coating on the outside.
The “diesel” drives are typically a higher ratio. So if you need a 1.5 ratio any x or xr 1.5 will work

If its an XR then its an XR. Nothing different internally.

Thanks to all for your help !!

Ok got it ! Open the box and the propeller dosent fit. The prop shaft is much bigger !
from what I read there is 1” and 1.25” so I am assuming mine is 1.25 ? Or there are more sizes ?

All XR's are 1.25 prop shaft from Merc, buy the 1.25 hub and you're good

Thanks

Is your prop a solid hub? If so, you might need a different prop.

If it's got the replaceable plastic hub, yep ^^^^^, just get the 1.25 shaft hub.