Hi,
I'm new to this forum but just recently replaced a heater channel in my '62. I got the "Bug Me" DVD on heater channel replacement. On it they show you how to put one in without lifting the body. Mind you it is more difficult. Mine went quite easy - screw a brace on the inside of the door opening (door removed) between the A post and B post remove all the body bolts and jack up the body from inside the car under the dash. Get the DVD though it is well worth the $30.
Col