94 astro cargo multiple problems (182,000)

I bought the van in "05". Always ran well with the exception that their has always been a loud humming sound from the rear. 1st question- what is that sound?
In the past year I have replaced the fuel pump/filter, new spark plugs, cap/rotor and wires, air filter, pcv valve,new Shocks, alternator, serpentine belt, front brakes and rotors, new muffler and catalyc, trans flush w/ new filter and gasket,cleaned out the egr valve and did a radiator flush. The van was driving beautifully for a while, with the exception of the humming from the rear.
Out of nowhere one day I start the van put it in drive and the van is dragging to pick up, at the same time I turn my lights on and a continous beep begins to sound as if my door was open. Gauges and wipers would not work either. At every stop the engine wanted to turn off. The acceleration was slow at first then it would drive ok. I drove another 15 miles and took it up to speeds of 45. I managed to make it home. Now the van will not start it ries to turn over very roughly once or twice then halts.
I had a feeling I would need to change the trans but did I just lock up the engine by trying to restart it? Did the humming sound from the rear play a part? If the tranny is burnt can the vehicle still at the very least turn on? Please help.

sounds to me like you have an electrical problem. directly behind your battery is a group of fusible links. On my 94 safari, one day one of them simply melted down. The engine died and everything electrical went south but the head lights. Sounds like it's melting and you are getting a ton of resistance. As far as the rear end noise I would suspect, well, the rear end. pop the cover and inspect.

thanks for your response. I took a look around and didn't find any damaged wires. I havent had a chance to take the rear end apart. my immediate concern is figuering out if i locked the engine. After some research, manually cranking the engine and an oil change I got the engine to purr like a kitten. So Here's what I did I replaced the fuse for the gauges, placed the vehicle in drive and experienced some serious lag. At the same time the fuse popped. When I place the van in reverse it kicks in hard causing the van to jolt, not so much in drive. I changed the trans fluid and filter about 2 months prior. The fluid looks good.Any ideas. Is it obvious the trans is gone. Why does the fuse for the gauges keep popping?