Definitely not a yellow belly. As for being het for anything, there is no way to know unless you breed it. The problem is, what do you breed it to??
Any normal that anyone gets from anywhere these days has the possibility of being het for anything because breeders unload their 50% and 66% possible hets as normals at shows and to pet stores because they usually can not sell them for any more than a normal.
The railroad tracks could possibly be an indicator of het pied but many normals that are not het also have this. The only way to find out for certain would be to breed it to a pied and see if you get any pieds.
You could also breed it to a 100% het pied but even in the slight chance that your snake IS actually het, you could still not get any pieds from that pairing. It might just be a wasted breeding.
Breeding to a pied is a win win situation because if you get no pieds, chances are really good that your new snake is NOT het pied but at least every baby produced would be 100% het pied because you bred it to a visual pied.