Thanks to everyone for the suggestions. The too-short front belts are due to
Cunegonde having Westy rotating seats and hence, missing buckle anchor
extensions standard on less accessorized Vanagons.

Does anyone know if I have to jump the brown wires emerging from the
driver's buckle? I have no annoying buzzer when I don't fasten the buckle,
so a PO must have disabled it. But will the van start/run? The battery is
currently disconnected while I tend to the waterpump.

I just cannibalized the rear lapbelt buckles/webbing/anchors to the front
seats, and behold, the extra 8" fixes the too-short problem. Albeit with a
half-twist because of the angle in the sheet-metal anchors. Now I need to
find another set of rear-seat lapbelt buckle assemblies. My back seatbelts
are only marginally useful with the short buckles inside the bench box!

--
Bretts

1983 1.9l WBX Ivory Westfalia "Cunegonde"