Volvo MD7a alternator

[Zeke69]

So I was replacing the second battery on my Islander last weekend and it was a little dark and i was trying to get done and head home. In the rush I switched pos for neg and you can imagine my suprise when I switched the panel on!
I know. Boneheaded move. Measure twice, cut once and all that.
After replacing several burned fuses this weekend I had my set my hand on my alternator and noticed it was warm. I hadn't run the engine so I new something was off. I checked and the key wasn't on but the light at the gauge panel was.
After a few minutes with google I'm now 99 percent positive I fried the diodes in the alternator with my battery switch job.
So the question is, are the diodes easy to change? I can always drop it off at the shop but I normally take on most small jobs myself. (usually with better results than my batt. installation) Also I've found that the alternator is fairly cheap. Anywhere from $85 bucks for the 50amp cheapo to $250 for a better 60 amp replacement.
Is it even worth it to try and mess with what is likely a 35 year old alternator?
Any experience with this situation would be appreciated!
And I'll take my licks as they come as well cause I know I'll hear about this one for awhile.
Layne