You do the best you can under the circumstances and hope it takes care of the problem.
Without the proper tools to confirm alt output, you are shooting in the dark. Hopefully you can buy some time with other less expensive checks and you never know , it may solve the problem. You would need a pretty hefty amp meter to confirm 130 amp output, but even half that amount should keep the lights from dimmimg.

 

FYI
By the time I finished tightening up ground wires everything was working normal so I sent the alternator back.

 

Thank you for the update. Always nice to hear it was not an expensive fix.

 

I just started having the exact same problem with my 07 Entourage. If you see this, would you mind describing a little more about the ground wires you tightened up (anything that will help me do the same)? Thanks!

 

It is hard to explain. When I popped the hood I could see a couple that were disconnected . Just started to wiggle and jiggle and found 4 or 5 more that were just plain loose . I think the worst ones were attached to the body rather than the engine which would make sense as those are the ones for the lights . A couple that were screwed into plastic ( 1 main and another for the device ) that I cleaned and moved to a better location (something more direct , actually attached to the frame/engine )
It can be a slow process but for me it had the required results