Probably not at all chains but at a local auto supply I got
Gates 5/16 (8.0mm) premium heater hose, made in USA.
It’s straight heater hose, buy what you need by the foot.

From: John H. Lauterbach
Sent: Thursday, October 17, 2019 6:07 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Hose from pressure cap on expansion tank to coolant overflow tank

Thank you, Dan.  I went to the local AutoZone and O'Reilly's and neither store
had anything close except for high-pressure fuel lines.  That is why I posted to
the list.  John

On Thu, 2019-10-17 at 17:44 -0700, Dan N wrote:
> cut a short section of the hose and bring it to any auto-parts store andthey
> will match it.
> On Thu, Oct 17, 2019 at 4:15 PM John H. Lauterbach <john@jhl.mgacoxmail.com>wr
> ote:
> > What are the correct dimensions (ID, OD, Length) for subject hose, andwhere
> > doI get it?  I have seen some hoses on list vendor websites that
> > looksimilar, butnot the same.
> > If one cannot get a direct replacement hose, what are the alternatives?
> > Thank you,
> > John