Is there any negotiation at the starting pay? I doubt it, but thought I'd ask, if you happen to know..
None at all. Good question, but the pay scale is set.
If you want/need more money, you could take that job and deal with the pay in the mean time, then you could transfer crafts and get into a higher paying job. Only problem is that you have to spend 2 years in the craft that you hired into. I'm sure you could climb the ladder in the mechanical department and get into a higher paying position pretty quickly. It's not hard, you just have to be a decent and safe employee, then bid on the higher jobs as they come up.
The best advice would be to get hired into the craft/department that you want to work in. You know Jason, I'm not sure how mechanically inclined you are or how your current job might have a positive effect applying for a job with UP, but with your experience working with & around electric motors might be a great IN to that diesel mechanic job. Locomotives are driven by electric motors... consider it... you might be surprised what could happen if you applied.
There are basically 3 departments at UP, Transportation (crews that operate the trains), Mechanical Dept (guys that maintain & repair locomotives & cars) and the department I work in, Engineering (maintain & repair the track).
In the engineering department, the entry level track laborer jobs pay $19/hr and go up from there.