Depends on the vehicle.  I am a mechanic by trade ( retired - 25 years an ASE Master Tech, 15 years a High School Auto Shop teacher ). Electrical systems was one of my specialties.  As an example; pulling a dash on a 1970 to 72 Chevelle is a 20 minute job.  The same task on a 1990 Mustang is 4 to 5 hours.  Some newer cars it is an all day affair just to get it out.  I have found the biggest problem to be people adding accessories with no real idea as to how to properly wire them in.  Most fuse blocks have spots to pull power with extra plug in ports.  But many novices cut into wires and overload circuits and cause problems.  A lot of stereo shops also do a poor wiring job. ... View more

     1967 Chevelle SS, 1967/8 Firebird 400 or 1968 Firebird Sprint w/ 250 cid/230 HP OHC,4 speed trans, Randel AMC 401/4 speed Gremlin X or Baldwin Motion V8 Vega.      Had a '67 Chevelle SS 396 close ratio Muncie and 4.10 posi 12 bolt rear end.  When I bought the car in 1975 the 396 was gone in place of a 1962 327/300.  I put a on a Q-jet with the stock cast iron q-jet manifold in place of the worn out AFB and put a dual point conversion in the distributor.  After many hours of fine tuning the car was stupid quick.  The car was totaled on the way to work when a guy cut in front of me at high speed.  Out of the 90+ cars I have owned it is the one I most wish I still had.      I really like the early Firebird.  I think they look nicer than the same year Camaro.  In the late 60's in High School there were a couple of these in the student parking lot.      Gremlin X or V8 Vega, who dosen't like a small car with a big engine. ... View more