i have and el on dual fual and i would really like to put an au xr6 engine or something like that into it in the near future, sounds stupid but what components of an engine get changed to suit running on gas? just wondering how much it could cost

In an EL, nothing, they're plenty strong enough for gas.

In other models. ie dedicated LPG cars, some have stronger rods, and changed compression ratios etc.

However throwing an AU XR motor in your car isn't going to give you magical horsepower. LPG in most cases for E-Series cars are made up of a mixer ring, this reduces air to the engine and creates a bottleneck. some are good, some are bad, chances are you wont tell the difference.

You could improve a few things with different types of throttle bodies, lpg injection etc.

either way, If you've sourced a healthy AU XR engine and your current engine is dying, it might be worth modifying the AU sump, or your cars K-Frame to fit it.

yehthats exactly what i was wanting to know, incase the engine decided to die on me if i could get a better engine such as an au one, cut and weld the sump and enjoy an engine that would be a bit smoother perhaps. i just wasnt sure about the process, whether you could just source another healthy engine, drop it in and it would run straightaway on gas...