Re: Cab/frontclip swap or driveline swap???
Don't worry about swapping from auto to manual stuff, it is just a few holes to cut in the floor, and swapping the pedal assembly out of your old cab (this requires removing steering column and brake booster, but not a big deal). As far as the tags, I believe the older (pre 1980) ones were on the drivers doorpost and the newer ones are in the uppper left corner of the dash, behind the windshield. I wouln't worry too much about getting a new VIN since you have the rest of yuor original truck with clear title, and the cops probably won't care or know the diff between a 78 and an 84. The wiring plug in for taillghts is different (changed in 1980, I believe) but if you are swapping boxes anyway it shoudn't matter. Just make sure the truck isn't stolen or somethinh and that's why the tags are gone.