In the meantime, to answer the OPs immediate needs: found this:
shimano Dura Ace shifter brake rubber hoods st-7700 New
No idea about source reliability.
Edited to add: see comment below by @
panzerwagon - he found troubling indications concerning source reliablity when he investigated a bit.
Caveat emptor.
Last edited by Hondo6; 03-29-23 at 04:44 AM.