Good Alt. wont charge when on car

[nac's95_240sr]

I have a 1995 240 with a redtop sr20 in it. recently i was replacing the thermostat and when i got it back together i find out that my alternator is not charging. we put a volt meter to it and with the car running it was at 10volts. so i figured i had a bad alternator. so i got the alt. of my 95 ka and drilled the hole out to make it fit and swapped the pully, took it to advanced auto and bench tested it ( i know it was done right cause i did the test) it puts out 14.5 volts. get home put it on the car with a fresh charge on the battery and it starts right up. well i let the car run for a while and it drains the battery and dies. i checked the connection and they are all tight and clean. any ideas? also my gauges didnt work when i started it and neither did my stero, and i couldnt rev passed 2500. i have searched the forum for hours now and only find where people have bad alts and some of the problems, such as the rpm, but nothing with an alt that puts out 14.5v and like i mentioned i haved checked and rechecked the connections. one ground wire, one power wire, and the two prong plug in. Thanks for any ideas

[zauber]

check your main alternator fuse.

[nac's95_240sr]

i already checked the fuse, thanks anyway