Ok, if you have a modern stereo in your truck, you will always have a small draw in your system.
The system draws amps, not volts, so the 1.5 volts doesnt make sense.
Here is a link on how to do a voltage drop test:
http://www.svapowerproducts.com/html/voltage_drop.html
If your battery is reading 11.4 volts it is way under charged, and needs to be put on a charger. A fully charged vehicle with no accessories on should only draw about 8 to 10 amps. 2-4amps for the battery and 3-5amps for coil. So amn amp meter should always show some outrput when the vehicle is running. If it shows more than 15amps with everything off, you have a bad battery. (cracked plate, warped plated, or interplate connector trouble, will test fine with every other test though)
As for the regulators, Transpo makes a electronic regular unit, HD unit, and XHD unit. The XHD unit you had is very expensive, like $30 I think, too bad it failed. Are you plugging the regulators in before mounting them? If so you are blowing them up by doing it that way, they need to be bolted down before being plugged in.
Get your battery recharged. Start the truck and take a voltage reading at the back of the alternator. Then phone me with it 519-732-8480 (I am out of the shop for another few weeks, that is my cell number)