A bit of a humourous aside: my father heard of a "1941 Jeep" for sale. I got REAL excited since that would be an MA or MB model jeep, with the slat grill verses the later stamped steel ones. Figuring someone had a seriously rare jeep we hot footed it out there.....turned out to be a 1951 M38A1 in VERY rough shape. Major let down, for sure--we'd even towed a trailer out there!
Anhow, the jeep your father has is probably a CJ5, a very good rig. I drive a similar 1974 model. Here is a link to some of my pics:
The Moonlight Rambler
I've got the metal top back on now, but haven't posted any pics of that other than the one beside my posts.
Now, I believe that the '71 was the last of the "short nose" CJs. That means that the front fenders are a few inches shorter than the later CJs. If you look at it, the front wheel well comes almost back to the tub. The longer nose on later models was to accomodate the V-8s and Straight Six engines that AMC started using.
In perfect condition, with no rust and 100% original, I would guess that it would go for $2500 to $4000 depending on your location and your buyer. However, that is an absolute guess, based on my experience here in Alaska (up here if it is 4x4 and starts it is worth $1000 regardless of condition!). Maybe another member of the board that lives closer can give a better feel for your area.