driveshaft advice needed

[4wdriver]

my 78 k20 has a two piece drive shaft with a 205 transfer case i would like to go to a single shaft.not sure where to start looking or even if there is a single shaft that would fit from another truck.this truck had 8in. of lift i took out the blocks in the back but still there is problems with the angle of the shaft.i should mention the rear spring hangers in the way back are the flipped kind used to add lift i left them in because i dropped the front to 3in. springs.