My old eyes cannot pickup the Xray sights on either my 365 or 365XL. Any recommendations for replacement sights? Do the same aftermarket sights fit both pistols?

Any aftermarket sights made for the P365 will fit it. I have Trijicon HD's and XR's on many of my pistols. I opted to keep the xrays on my P365's because they're low profile, and I pocket-carry the P365's.

For shooting steel matches, I've gone to fiber optic sights. They're trendy these days, but the reason I did it is because in daylight conditions, they're easy to see and they seem more precise. For low-light conditions, they're not useful for much more than a silhouette, except that a fiber-optic rod that goes all the way through the front sight (front to back) will illuminate when pointing directly toward a light source. Whether its visible or not depends on the lighting conditions and the intensity of the backlighting.

I find that with glasses, I can't focus on the front sight as much as I used to, but with fiber optics I can still see the front sight well enough, because it's so visible.

I have been wearing glasses for about 3 or 4 years now. Ever since then my old eyes have had trouble focusing on the front sight. I just recently put a Trijicon fiber optic sight on my M&P. At the indoor range (it's kind of dark in there) it helped a little bit, but not as much as I was hoping for. Outside, or in brighter light, it helps a lot.

I install Trijicon HDs, ( in whichever of the two colors your eyes pick up better - I prefer the yellow/green version, ) because my older eyes pick them up better and they work great for malfunction drills, too.

IIRC, the HDs fit both versions of the 365. ( Models SG103O and SG103Y )

https://www.trijicon.com/produ...or-sig-sauer-pistols

I've been more than happy with XS defensive express sights on my Glock G30. The front dot is huge and has a center tritium insert. The rear sight is a shallow V with or without a tritium insert. The sight come up fast and there is no not-seeing-them. These sights are available for the P365. The tritium vials are Trijicon and some XS sights have Trijicon etched on them.

https://www.xssights.com/Products.aspx?CAT=13224

Here's the sights on G30.

Truglo TFX Pro, fiber optic with tritium. Very easy to pick up in both light and low light.

If the X-Ray sights are hard to pick up, it might worth a conversation with your optometrist. We have a local guy who will measure for the distance between your eye and the front sight and prescribe lenses for your specific needs.

Yeah... Xray sights have one of the more obvious/prominent front sights on the market. Something like Trijicon HDs or XS Big Dots will potentially only be marginally easier to pick up, and may not make enough of a difference for you.

So as mentioned, if you're having issue with the Xrays, it's time to have a conversation with your optometrist. It's you, not the gun.

Another option is to look at installing a mini red dot like a Romeo Zero on them. (The XL slide is already optics ready, but the P365 slide would have to be custom milled; or you can just swap the XL slide with optic back and forth between the two frames.) Red dots may be easier for you to pick up than iron sights, since you're focusing farther out on the target instead of on the closer front sight. But again, it may or may not be enough for your eyes, depending on your specific situation.