What weight is your 49? I believe NAPCO did produce 4x4 units for earlier 1 ton trucks. Half tons didn't get them until the were available from the dealer in 55.
It requires a few things to work so best to get all the running gear. Like SWEET said, it makes your truck extremely heavy and all those massive gears turning kills speed and gas mileage. I get about 9 mpg with a 350 V8. But nothing better than a NAPCO in my opinion!
Now you could try to place your 49 on top of a late model frame and running gear but I think you will find the frames are too wide. You might be able to shorten late model axles and make it work. But you are in some tricky territory.
