Charging system not working!

I've had the alternator taking out and checked, the battery taking out and recharged and tested under a load, both are new the battery is 5 months old and alternator is two weeks old.
Ive changed the negative battery cable, i know there is a fuseable link that connects the back of the alternator to the starter back up to the battery positive terminal. i took that out and just put in a wire straight from that to the battery terminal itself, because i thought i blew the inline fuse. its a 3 wire, internal regulator alternator. im not seeing a fuse in the fuse box for it, or an "idiot light" like ive read. I may be wrong,, I'm just frustrated because I need this vehicle for work and do a lot of back and forth driving, (I'm in the military and sometimes they get confused as to where we should be). I do not want to take it to a mechanic because I'm tired of pouring money into it that way and this should be an easy job, but if someone can help me out who knows what they are doing! Please help!!

Steve,
What vehicle are we working on here and is it original equipment configuration? Where does your negative battery cable connect between (wondering if maybe if you might have another bad ground path)? Give us a little more information and hopefully someone here can pinpoint your problem. And thanks for your service, by the way, and amen to your unit getting confused where you need to be sometimes - been there, done that.

Oh, I'm sorry I forgot that part. ha. Its a 1978 chevy c20, its got the 350 in it. I have no real accessories just cd player, and lights. its a simple configuration, the original ground was mounted above the alternator bolt holder. its worked fine since ive had it so i just unscrewed it and put a new cable on.

if everything works off the truck what is telling you it dont work on the truck .. a trick i always did was to stick a screw driver on the back middle bearing area of the alternator while it is running and if it is putting out the screw driver will stick like a magnet ..

With the engine runing and all things conected. disconect the positive cable. if it continues to run it is putting out if it dies then it is not.. did you say you ran the heavy red wire from the alt. to the positive post on the bat when you pull off the pos. cable be sure the red wire is still attached to the bat cable?

Hi Steve,the most common problem is wire strands breaking off internally at the regulater plug.Alternaters need juice to make more (no magnets) The heavier regulater wire,pretty sure it's red, ties back into the charging output wire (batt) in the harness near the back of the passenger side valve cover,so it should have battery voltage at all times. The other regulater wire (white?) should be switched Ignition source. If you put just any batt source to it,you can't shut the engine off. (backfeeds) Hope this helps you,Hank