Remember that when the Revell kit was first released the SR-71 was still very much secret, so the mould makers had to go by photos and conjecture. When the Monogram, Hasegawa, and Academy kits were produced, there were far more photos and information available.
I'd compare to photos and see which looks right. Either that or find a museum aircraft and measure : )
I've got a stack of YF-12s & SR-71s sitting here. Many, many years ago I built the Revell SR-71, (the real one, before Monogram merged with them), the exhausts were HUGE. A few years ago, I built the Monogram kit, (their regular one with the drone). Those exhausts are probably 3/4s the diameter of the old Revell kit's. I have the old Revell YF-12, same kit as their SR-71, basically, next to an Academy SR-71, which I assume is a copy of the Hasegawa kit. Its exhausts are in between the Revell & Monogram kits'. I've been trying to get my paws on a Testors YF-12A, so I don't have it to compare. Anyone know which kit has the correct sized exhaust? Not that it matters, I'm just curious.
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