The cargo barrier was an option on the "wagon" style roofed Broncos.
If there is no back seat, and the cargo barrier has no bolt holes across the top edge (for bolting a roof down) this is probably how your truck was optioned.
To be certain, the first three digits of the serial number will tell all....
U13... Bronco roadster (66/68)
U14... Bronco sport/utility (half cab, 66/73)
U15... Bronco wagon (66/77)
The fourth digit will give you the factory engine size
For '71 "F" was the 170 ci 6 cyl, and "G" was a 302.
As for value, without seeing the truck in person, and not knowing what the demand for Early Broncos is in your area, it is tough to guess.
From the pic you posted though, the truck looks fairly original, and fairly straight, it would probably be valued at the higher end of the original price range, keeping in mind that un-cut original Early Broncos are getting quite hard to find, but later trucks with power steering and disc brakes are sometimes more sought after...