well my electrical system is being stupid

[w/gcd72]

since ive bought my truck in june, ive started to notice more and more that the lights flicker all the time while driving. ive had to replace one, and the dash is only lighting up the speedo, and only half of the gas gauge lights up. me and my dad have tried to figure out the problem, we know its not the alternator, we think it might be the regulator, but we don't know. im new, and he hasn't worked on his own cars/trucks in awhile. any idea's?