Dan, there are four bolts that hold the glass frame to the C-shaped channel olblu49 speaks of. Once you remove the cardboard panel from the door, you can see them through the two openings toward the top of the door, once you roll the window up or down to have the channel meet that level.
Here are the directions as presented in the "servicing Chevrolet Truck Cabs (1947..1948). I'm pretty sure nothing changed for 1949.
"First, remove the control handles and door trim.
Then, raise the door glass and remove the four clutch-head screws which secure the glass frame to the regulator mechanism.
Roll the mechanism down all the way. Then rotate the glass in its opening, as shown, and lift it from the door."
Of course, you can't see the picture, but it shows the latch end of the glass being low in the door, and the leading edge being lifted up.
I'll scan the pages and send them to you, if you'd like to see them. Let me know.
There's nothing in the booklet about removing the regulator.
