So to keep this simple...

im 25, 158ish and range sometimes 

I'm having trouble in taking the calories I need to gain muscle mass

i work for FEDEX express as a courier and I work my butt off everyday and in the summer it's 10x fold with the heat. 

Any tips on how to get my calories in? I'm prepping my food but I still fall under to caloric deficit :/

Any chance of carrying a small beer cooler type container in the truck and keep it full of protein drinks and/or fruit or other healthy snacks - especially nuts (walnuts, almonds, peanuts) to help you get in extra calories while you are out on deliveries? The quickest and easiest way to add a lot of calories quickly is increase your fat intake. It needs to be healthy fats though like nuts and coconut oil. If you pack some tupperware full of rice and chicken and add a couple of tablespoons of coconut oil to it, you quickly add another 230 calories to the meal.

John

Okay thank you! And yes I totally can! I'll just pack with healthy fat treats and protein drinks. I have no trouble hitting my protein per day of 1.5 per pound I was just worried iof gaining too much fat weight

John is spot on! Carrying your own food is the best way to go about it - I used to, and still do sometimes, carry food with me if I am busy during the day and don't have time to prepare anything.

You can also look at making shakes so that you can cram a lot of food in at once, without having to actually 'eat' it all - you'll just be drinking it. You could even take a shake with you as well as all your actual food :-)