New engine Ram Van 2500

Hey guys. I'm new to these forums so please forgive me if I ask questions that have already been covered.

I recently bought a 1996 Dodge Ram Van 2500. It's a great van for the weekend fishing trips and camping trips. The problem is the gas mileage.

It's got ~113k miles on it but it still runs great. It was very well taken care of. So far all I've had done is an alarm, keyless entry and remote starter installed.

You hear all these commercials for new vehicles with "efficient V8" engines. I was wondering not just if it's possible but how much of a hassle would it be to have a more efficient engine installed?

Aside from other routine maintance, what other options are there to save gas?

Thanks for the help and I look forward to being a part of these forums.