Use stress cones at each end of all phases
of jacketed URD cables.
Don't use porcelain.
One major manufacturer is Joslyn in Chicago.
They manufacture at least several, and have printed
instructions on how to install.
We use 3M Quickterms, because they are inexpensive and
fast to install.
Make certain you install MOV surge arresters (Ohio Brass) at both ends of your cable(s) as well.
URD cable can be a big headache......try to use EPR, not
XLPE-TR. XLPE-TR will 'water tree' within 18-20 years....inherent to the cable. EPR will go for 40 or more
years.
Also, make certain the cable insulation thickness is %133, and has a jacketed neutral. For single-phase residential feeders, use a full-neutral. Substation getaways: use 1/3 neutral.