The Testor's/Italeri kit is the most accurate of the bunch. The nose landing gear bay is too shallow with very little detail, (the Monogram kit is much better in this spot), and it has the same problem as all SR-71 kits in that the engine turbine aft face is way too far back in the nacelle. The Monogram, now Revell, kit is good except the fuselage cross section is way too shallow. This makes the cockpit much too wide. It also has the plastic, triangular radar absorption panels on the outer nacelle chines and shouldn't have. The main landing gear is good, but not as good as the Testor's. There are a couple of other shape problems. The original Revell kit was the first on the market in 1968 and is fairly good. The fuselage is too deep and there is absolutely no detail on the kit. The cockpit is zero.
Some people say the Hasegawa kit is the best, but I disagree with that. The fuselage shape is wrong, the landing gear bays are not as detailed, the cockpit is not as good, etc. Some of the kits have the d-21 drone included. NO SR-71 ever carried the D-21 drone. Only the two M-21s did that. They are modifications of the original A-12 and have a different forward and aft fuselage from the SR-71. Just putting the decals for 06940 on an SR-71 is not accurate. The Trumpeter/MiniCraft kits contain what is called J-58 engines, but they only bear a vague resemblence to the real thing. The entire engine is actually the same diameter for the whole length while the kit version is MUCH smaller at the front. They also have a large engine access door on top of the nacelle and that is pure fiction. On the real bird, the whole wing tip/nacelle section folded up for access to the engine from the bottom.
The Trumpeter and Mini Craft kits are the same kit.
The original Revell and Advent are the same kit
The Academy and Hasegawa are the same kit.
The Revell of Germany and Monogram are the same kit.
Darwin, O.F.