Alternator problem with speedo problem?

[Red V6 Raider]

A few days ago I noticed a problem with my speedometer. When I start my car the speedometer just starts climbing while I'm still idleing. Once I start going it seems to be OK but I don't know what it means. I also have been having a problem with my electrical power while driving. I've noticed my lights start dimming while I'm driving(I don't have a aftermarket system or anything to unusually drain power), after I saw my lights were dimming I looked down at my voltometer and it was just kind of dropping down in little surges. This is while I was constantly moving staying in gear.

I think these two problems may be related since they both seem to have showed up at the same time. Anyone else have these problems? I think I've heard about the speedo problem on here before. I'm thinking maybe I should replace my alternator but it's quite a bit of money and I don't want to spend it unless I'm pretty sure it will fix the problem. Please help me! Thank yOU!

[ka50]

Alternator is about to take a crap. So watch it closely. You might also get "idiot lights" go on too for no apparent reason.

[Red V6 Raider]

you think that's why the speedometer is acting crazy too?

[speedy-v6-camaro]

My alternator went out last night....and about a week ago it was doing the crazy drop in voltmeter thing. I still made it about 60 miles while just on the battery....most of it was at 100+ speeds though.

[Red V6 Raider]

So you're saying I better get a new one pretty quick then, huh ;)