driveshafts extended/6" Susp. Lift Kits

[Budweis]

anyone know what i might expect to pay to get a couple of driveshafts extended? i was going to go with a 6 " lift but it says on spring type only adds 4" front and 5 1/2 " back so was thinking bout the 8" as it goes a true 8" of lift front and back but i understand will need the driveshafts extended so wanting to find out cost before get into. or does anyone have a link to a 6" spring suspension lift kit that adds a true 6" front and back? no block Kits please. seems to me the easiest part is going to be installing as i spent way too many hours trying to find what i need lol. its for a 1970 c20 3/4 ton 4x4. matter of fact if anyone has good links for reasonable suspension parts for this vehicle please leave here as ive only found like 3 or 4 places that even have anything for this truck.