Yes- hard to tell whether it's the rear pan seal or rear main seal leaking. FYI, there are also two (maybe three) different rear main bearing seals. Choices are the OEM 2 piece rope seal, a neoprene 2-piece seal, or a one-piece 351-W seal (requires block machining). On stone-stock Panteras, oil pan removal means cutting the welded under-pan crossmember and e-brake bracket out for clearance. Making these removable was a post-Ford factory upgrade.
The seals all have their difficulties and all can leak from one or both sides of the main cap to block where the little square inserts go, or if the sheet metal oil slinger (to direct excess oil away from the rear seal) is left out. Most builders stagger the seal ends (either type) a little so the seal joint does not line up with the cap-to-block joint.
Rope seal- Can leak at the ends without some sealant on both ends where they get hand-trimmed to size with a razor blade. Easy to underestimate the size needed. High crank drag until broken in.
Neoprene seal conversion- Can leak at the small hole left in the cap when an OEM rope seal locating pin is driven out, unless the main cap pinhole is filled with something (early blocks). Seal can also leak if the crank journal is worn or ground undersize more than about 0.001". No break-in necessary.
One piece neoprene or Teflon seal- can leak if the crank journal is worn or ground undersize more than about 0.001". Also takes block/rear cap machining oversize about 1/4" to fit the large Windsor seal (I've only done one and that's been a decade or two....). So a 1-piece seal is not a cure-all.
Finally, BOTH the two-piece main seals can be changed with the engine AND ZF in place. You just use a popsicle stick or something similar to not scratch the crank when lightly tapping the seal around the journal. The one-piece seal absolutely needs the ZF pulled to change it. Good luck, all.