A truck is heavy enough to carry batteries, but you'll use up much of your cargo capacity carrying those batteries. Its a trade-off between size enough to carry the batteries and the overhead (weight) required to carry them and the weight they add directly.
I think electric power might be an interesting project, but I'd rather watch you do it than mess with it myself.
How much and how far are you going to drive this truck? If economy is your goal and you understand that both initial cost and incremental costs make up the economics, it isn't hard to model the lifetime cost.
Of course you have to make some assumptions to do that, but my solution to that problem has been to model several different assumptions regarding future fuel costs and future usage.
In my case, modeling a gasoline motor I have against a Diesel I'd have to purchase, and assuming I understand the costs of each swap, it just does not make sense to go Diesel. But a key part of that calculation is that I'm not driving this truck very far most years.
I ran the numbers first to be sure I wasn't nuts in thinking a gas motor was cheaper to do, and second to be able to speak with confidence in dialogs like this.
To someone else I'd say know how much you're going to use the truck and your cost going each way, then model the costs. If economics is your most important consideration your answer will come from the model.
Some of the others here are clearly biased toward Diesel while I'm a fan of big gasoline V-8s. Your choice between one of those or possibly electric power needs to suit your own preferences and priorities.
