These lock washers replace the functional, but incorrect, lock washers with the old part number that are provided by Porsche:
PET '65-69 911, Fig 4-03-00, #15 999.523.107.01 Lock washer, old version, -68 Qty: 2
WET '65-68 911 Fig. 4-2, #28 999.523.107.01 Lock washer, old type Qty: 2

They are used with the earlier version's parts:
PET '65-69 911 Fig. 4-03-00, #13 901.347.315.00 Joint fork, old version Qty: 2 NLA
PET '65-69 911 Fig. 4-03-00, #14 901.347.316.01 Articulated bolt, old version Qty: 2 NLA
WET '65-68 911 Fig. 4-2, #05 901.347.293.00 Joint bushing (housing), old version Qty: 2 NLA SS: 914.347.057.00 (New version) Qty: 2

Material: Stainless steel, 304, 1.0mm
Finish: Mill-finish
Weight: 3.5 grams ea.

The price is $5.42 each, $10.84 per set of 2.
Shipping within the US is by USPS Priority ($0.60).