This topic comes up from time to time; Figured I share what I just got done on my 49 to show folks another option for your workbox.
I needed something, the underseat "storage" is really impractical and even just using the truck to bring more than one kid to school was not ideal with them having to throw their stuff in the box. My oldest daughter started renting a booth in the local Farmers Market and that was just a lot of loose stuff that didn't really fit in the cab and was really too light to sit outside in the box.
So I traded a buddy who is an aluminum fabricator my .45 Rossi Ranch Hand (which I already miss, but hey) to take this commercial grade aluminmum work box (1/4" aluminum, so it's weldable) and section it to fit in the 49. We left a little but of wiggle room as a contingency, and she fit beautifully.
The best part is (for myself), I didn't have to relocate the spare tire:
1949 Chevrolet 3/4 Ton - Still Solid. Regular Driver OT Vehicles: 1925 Hudson Brougham Super Six 1950 Chevrolet Styline (Parts) 1952 Canuck Pontiac Sedan Delivery (Well Underway) 1973 F250 4x4 Highboy 1977 F250 4x4 Lowboy
