To elaborate on what 3B said...
The 302 probably has side mounts. You will need the front mount plate from an earlier GMC or a 235 Chevy.
Being in a 2-ton it probably has the bigger flywheel and clutch. If the engine in the '49 is a 235 you can use that bellhousing but you will need to find a 6 bolt GMC pickup flywheel. A '54-55 will have a 6 bolt 6V flywheel and a '56-59 will have a 6 bolt 12V flywheel.
