Hey Lucky,
Sorry to break it to you again, but you definitely have a 51 and not a 50, neither a 52. 48-50 had a small back window and a different instrument panel. 51/52 instrument panel had two separate clusters for the gauges and speedo. 51/52 also had a large back window like in your cab.
Here's the 51/52 instrument panel.
Note how small the rear window is in this 48-50 cab.
As you know, the 48-50 front clips also differed from 51-52. That's an easy difference to spot. However, spotting differences between a 51 and 52 could be hard and not easily seen to the unknowing eye. I'll try to explain the differences.
All of the hood trim is different on a 51 than on a 52. Additionally, the hood, itself, is different on a 51 than on a 52. The 51 hood has three opening in front, while a 52 only had two openings (with the center not being cut out at the factory during production of the hood).
Here's a hood side trim from a 52 and 51 below. Note the differences.
Here's the front end of a 52 and 51 below. Note the hood difference and FORD letters added in 1952 (similar to 1948-50). Note where the V8 emblem went on the 51. If the emblem isn't there, then the truck was a 6 cyl.
Your bed is also a 51/52 style. Sometime in the late 50s, Ford switched the design. 1948-50 beds were somewhat different from 51-52 beds. The bed on the truck looks to be a 51/52 style. 1951/52 beds had flat bedsides, while 48-50 had a stamped in (raised) portion. The stake pockets on 51/52 beds were also square, while 48-50 stake pockets were round. The latches on the tailgates were also different to accomodate for the difference on the bedsides. The 48-50 tailgates had the latch in the upper roll of the tailgate, while the latch in 51/52 tailgates was below the roll.
Here's a 48-50 bedside.
Here's a 51-52 bedside.
Here's a 48-50 tailgate and a 51-52 below.
There were other differences, like the inner fenders were attached to the frame at the bottom in 1951, while in 1952, the bottom attached to the cab. The holes for the heater tubes were placed differently in 1951 cab cowls, than in 1952 cowls. The VIN tag was affixed in the upper right hand corner in 1951 models, but it was eliminated in the 1952 model year. Then there were 5 Star and 5 Star Extra Cab (deluxe optioned) trucks. I could go on and on about these trucks, but I'll just bore everyone.
If your front suspension is still stock and the right frame rail wasn't chopped up, look for the VIN to be stamped around the front suspension area. You may need to scrape off crud, grease and rust. VIN should look something like this: F1R1RH12345. If you find your VIN or have it on your title/reg, post it, or PM me and I'll decode it for you.
Besides the HAMB, you might also want to visit this forum,
1948-60 Ford truck forum. There are a bunch of knowledgeable guys, including myself, on there that can pretty much tell you everything you need to know when it comes to these trucks.