Truck pulling to the right slightly, what can i do to fix?

The front is aligned to the back, and it sounds your rear axle is out. The front has to be done too.

A good alignment is much cheaper than tires.

 

All the axels are aligned to the truck centerline.
The center line of the front axel is held by the spring center bolts in the axel saddles and are largely not
adjustable front and back.
The rear axels are adjustable front to back via adding or removing shims and are aligned to the truck centerline.

 

Yes, definitely sounds like the rear is out.
Check the spring bushing on the driver side drive axel.
If the bushing gets too much wear it lets the axel #### back towards the rear of the truck causing miss alignment.
You can get a pretty good idea if your rear is out by using a piece of string and ruler.

 

Why not just get a 3 axle alignment and check the toe at the same time? I mean I get not wanting to waste money, but how much money and TIME are you going to waste having to go back and have the other axles done? What do they say? Something like stepping over dollars to save pennies?

 

MY advice:
Pay for a 3 axle check. You will get a Report.
Adjust and pay only the axles Out of Adjustment.
Problem solved. Do it at least once a year.
Money well spent.
Good luck.

 

That drop axle needs to be checked for alignment too unless you never use it

 

You can check your rear axle for alignment with a string and a ruler and it won’t cost you anything but your time.

 

Ask around and find a good alignment shop with a good reputation. Not a TA. And just because a shop has the latest and greatest Lazer alignment system doesn't mean they know how to use it.