Subject pretty much says it all: I have a 1949 Chev 1.5 ton 5-window with it's original radio. Knobs are crisp, but I got a repro set. Do the old knobs pull straight off???? Anyone remember how many fasteners under the dash hold it in? I'm looking up there with drop light, but a few tips might prevent me from damaging something by missing a screw, etc. It's time to pull the old radio out and see what I've got and I just want to be careful. Not sure how practical it is to have it rebuilt....I know there are modern, "replicas," but there is something to the original set. Thanks, Dennis