There were at least three different suppliers of the F-4 370-gallon external tanks that were slightly but clearly different externally. See http://tailspintopics.blogspot.com/2013/06/things-under-wings-f4h-f-4-phantom.html
Few F-4 kits provide the original McAir tank, which did not have a constant diameter at any point from either end to the middle and did have flanges on both sides at the midpoint of the tank. Jeffrey Kubiak of Hypersonic Models has stepped into the breach:
These are 1/72 scale, accurate in size, and include the handed pylons to which the tanks were attached. The resin in my example, provided by Hypersonic, was flawless. (These are also available in 1/48th.)
Hypersonic also created a 1/72 set of the Navy outboard pylons required for other external stores, also handed (because of their attachment to an angled wing spar) and excellent.
Both kits come with detailed installation and painting instructions.
This is Hypersonics website: http://www.hypersonicmodels.co.uk/