Having worked in the SR-71 Blackbird program for 12 years and been a modeler for 50+ years, I am familiar with the various SR-71 kits. I would recommend either the Italeri or Monogram/Revell-Monogram versions. Both are excellent representations and both have their good and bad points. The Revell kit that jimbot is talking about is the original Blackbird that was released in 1968. It is OK, but lacks much in the way of detail. The parabolic dish radar antena is correct for the YF-12A, but totally wrong for the SR.
The Monogram, now Revell kit has the best nose gear well and an excellent representation of the David Clark 1031 pressure suits for the crew. The overall fuselage is too shallow for the width and thus makes the cockpit too wide. There is a rectangular embossed area on the outside of the rudders which is incorrect. That panel is present on the full scale bird, but it should be flush with the rest of the rudder surface, not raised. The decals for all but the very latest releases are typical Monogram. Very thick and basically unuseable. The chine running along the outside of the nacelle from the air intake to the leading edge of the wing has the triangular shaped radar deflection panels and should not have them in this area.
The Italeri kit has a very shallow nose gear well with NO detail at all. The fuselage is more accurate in cross section and has the RWR bulges on the nose just aft of the pitot tube. The nose also has the OBC or Optical Bar Camera window. The fuselage chine bays have square openings for the chine cameras, but they are in the middle of each compartment instead of the aft end as they should be. The overhead view of the nose chine area tapers too quickly between the windshield and pitot tube. This is closer to the A-12 profile. The decals are excellent.
All Blackbirds had aluminum particles imbedded in the main gear tires during manufacturing and have a distinct silver color. The nose gear tires are normal black rubber. The "turkey feathers" on the exhaust are black, just like the rest of the plane, not silver as depicted on many models. The overall color is flat black, (not dark blue as some claim), but it fades to an extremely dark gray after some use. Different panels can have a different amount of fading. The nose section had 3 interchangeable versions and frequently was a noticeable amount different in darkness from the rest of the plane. The 3 noses were, test nose filled with ballast, OBC camera nose and SLR / Side Looking Radar nose. The afterburner flame ring is shown just forward of the blow in doors on the aft part of the engine nacelle. It should be about 6 scale feet further forward. This same problem exists on ALL Blackbird models. As jimbot mentioned, both the Italeri and Monogram kits include the D-21 drone. The Italeri one has more detail and is slightly more accurate in shape. He is correct in stating that it was never flown on the back of any SR-71. There are several SR-71s on display around the country at various museums and several of them have D-21s displayed on their service dollies adjacent to an SR-71. Two of the A-12s were modified on the original assembly line to be M-21s or drone mother ships. 06941 was lost in a mid-air collision with the drone on the 4th launch attempt. 06940 carried the drone on several captive carry missions, but never launched one. She is currently displayed with a drone on her back at the Museum of Flight in Seattle. The only other airplane to carry the D-21 were two specially modified B-52H BUFFs. They made a dozen or more successful launches, but none of the 4 operational missions over mainland China returned any imagery due to various mechanical failures.
Darwin, O.F. 