If you see anything that looks like a big "X", it's an "X" frame. If you don't, and it looks like a ladder, it's a ladder.
As you know, it doesn't really matter. Drop outs are 55-64.
Coil over shocks is the wrong term. It is coil or coil with control arms or leaf. They did not use coil over shock. They did not have a coil spring with a shock in the center. I personally would pass on a drop out rear. You may have trouble finding the ratio you want and other internal parts. They have a greater leak path area. Go more modern 10 bolt, 12 bolt, D44. The diffs are usually dated. Got to clean and brush and scrape and search the internet. Whatever you get you will have some fabrication to mate to the 54. The width is important. WMS to WMS should be close. Number of lugs is important.
Any diff that you don't see and hear run has to be cheap. Free- $200. A junk yard is not where I would go unless it's a good old boy type. Check local Craigslist. Take off the drums and the
diff cover to inspect the brakes and check each tooth on the ring and pinion. Spin it.
The ring gear IS marked with the ratio. You could spend $600 more on a rebuild easily.
As the guys have said: Torsion=60-62. IFS and drop out= 63-64.
