Iron Shipwright makes a couple of post-war mod Fletchers in 1:350 scale. They are the Renshaw and Jenkins. The Jenkins includes the tripod masts and post-war weapons (weapon ALFA, 3-inch twins). I have the Jenkins, the Renshaw doesn't have a tripod.
I was concerned with the quality of the masting, based on past experience with some of ISW's masts, but the engineering & casting method of the masting has improved so that it went together well.
Otherwise - no aftermarket. You may have to scratch your own. For that 'Anatomy of the Ship - The Sullivans' may be your best reference