Are the end pieces removable from

[timelord]

the lug section of the cases with leather straps such as the 18K Yellow Gold 114234 Daytona
and
the gold 116139 Datejust?

These modern cases on leather straps appear to be different from the ones with metal bracelets and from the vintage versions with leather straps.

[kilyung]

I can't speak for the DJ but on gold Daytonas you'd have to remove the bezel to remove the endlinks.

[Tools]

No..or at least not easily. On strap Rolex watches, the endlink is attached to the case. The bezel needs to be removed and the endlink taken out of the machined notches underneath.

Once that is done, the bezel can be replaced and the notches are covered except at the very extreme sides..