Old MacBook power adapter on new MacBook Pro? I have a 60W power adapter from my old 2008 MacBook. 

Can I use this power adapter on a new 13" MacBook Pro, which also came with a 60W power adapter?

However the two power adapters have two different modell numbers.

Can there be a problem using the old one on the newer 13" MacBook Pro?
Yes, as long as your new MacBook Pro is of the 13" variety, then you will have no problems.  

While Power Adapters technically have different model numbers (to associate them during repairs), the wattage is what you need to look at when considering to use on on a machine.  15"/17" MacBook Pro's require 85W Power Adapters, where as, the 13" MacBook Pro and MacBook use 60W Power Adapters.

Hope that clears it up for you.