A cautionary note from across the pond - when I first took my 49 pickup on a test run the exact same thing happened - ah loose latch / catch i thought - NOoooooooooo - the chassis was cracked on both rails and the gearbox cross member was in three pieces - only the cab holding the whole thing together - only found this AFTER buying, but in fairness very difficult to spot, hey ho that's life. Now looking forward to driving it after a full rebuild.
All the best.
Andy