Reference usaf dwg 56b23624, for special markings
A tachometer that is driven through the media of a mechanical connection and includes provisions for fixed mounting.
NSN 5950-01-239-8821
NSN 6105-00-630-0378
NSN 5965-01-387-9976
NSN 6150-01-051-1678
NSN 5998-01-634-0604
NSN 6650-01-462-9709
NSN 5905-01-217-3106
NSN 5998-01-056-6546
NSN 5935-01-054-0866
NSN 6610-01-499-0776
NSN 6130-01-109-1158
NSN 6620-01-504-0997