IIRC the C-4 was constrained (size wise) by the need to deploy on old Polaris boats. The D-5 had no such limitation as the Ohio class was built with larger launch tubes.
Seems right. Comparing Trident II with Polaris A-1, I didn't realize the size difference between the Polaris family and Trident.
Now maybe someone will make Russian SLBMs and Chinese.
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Thank you Kim for the crest
"Never fear to try on something new. Remember that the Titanic was built by professionals, and the Ark by an amateur"