OK, whats going on with my truck?

so today at work a friend of mine does a little burn out. i just laughed and said is that all its got. he says these things are so little it will do it all day,and takes off roasting the "TIRE" until 4th gear. now we have what looks like the same trucks silver,single cab,4cyl,4wd,5spd. i figured i would see if my truck would do the same, now i dont normally run my truck like this but i just wanted to see what it would do. i rev'ed it dumped the clutch got 1st gear and a cherp in 2nd. not to be out done i tried it again same thing i thought man my truck has no power,so while he was laughing at me he says hey you got posi trac. was this an option in 08 on single cab 4cyl i thought i bought a plan truck or maybe i dont understand how the rearends work. but every time i tried a burn out it left double black mark. could some with knowledge of rearends tell me if this really is a posi unit or if something is wrong

 

you have no posi...open diff is what you have

 

OK, what's going on with my driver?

-your truck