Forbes reports Technology Refresh 3 (TR-3) will be retrofitted to Lot-10 on and TR-3 will allow upgrade to Block-4.
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The retrofits require about 14 days of downtime and will be performed by Lockheed field teams during scheduled maintenance.
The UK had 15 of the current 29 aircraft delivered up to lot 9. So 14 of the currently delivered fleet plus those on order would appear to be eligible. (The lost one was the 18th for the UK)