Sounds like the 2-speed rear gear ratio adaptor, used to keep the speedometer in calibration when shifting between the two different rear gear ranges. I've only see vacuum or electrically shifted units...

Mike B smile

Last edited by Mike B; 08/18/2024 7:00 PM. Reason: spelling

Mike Boteler

1956 Chevy 3100 Resto Rod
1952 Willys M38 Army Jeep
1983 Jeep CJ7 Laredo
1984 Jeep CJ7
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Silver Spring, MD