Fueling & Injection - Fuel pump for 99 sierra 2500

Hello, I have a 99 sierra 2500 6.0L, the fuel pressure is low 50psi, can I just replace the pump and not the whole sending unit? I have seen on ebay they sell just the pump, but the people at the parts store say you have to replace the whole thing.
Thanks,
Jeff

You can get the whole thing for $142 from here, why bother with a pump swap:
http://www.jdsperformance.com/index.asp?initemuid=1089&fcmd=item&inmake=0

What is wrong with 50 psi fuel pressure? That is within OEM specs.

I thought I read fuel pressure was supposed to be between 60-65psi, I guess I'm wrong. Well if they fuel pressure is good than my hesitation is coming from something else.
Thanks guys,
Jeff

Looks like the fuel pressure is supposed to between 55-65psi, I'm going to double check my pressure today.

Not good my pressure was at 49psi at idle.