[Old Tele man]

...yep, that's the same unit that I had. Although, I was wrong about AC-voltage coming from the speedo-unit and the function of the R and C...36 years of intervening life will do that!

...the original designer was George Ctirad Spacek (whence the name 'SpaceKom') who patented his design as 'Fuel Consumption Indicator' USPatent 3,673,863.

...after reading the instructions my memory was jogged about "Technical advice" coming from Mr. Steve Cappucio, DST Industries, Romulus, Michigan...always struck me as VERY odd that SpaceKom was in Goleta, CA, but you had to contact a guy in MI for technical questions.

...per the instructions, the Resistor (R) was used to compensate for too much voltage from alternator and the Capacitor (C) was used to dampen needle fluctuations.

...one intersting fact that I DID learn from that device was that MOST US cars (but not all) had the speedometer shaft turning at 1,000 revolutions-per-mile, or 10-times per tenth-of-mile (wonder WHY the Olds 88 and 98 had the "odd" number of 778 revs/mile?).

...for information about Spacek's later "Digital Flowmeter" GOOGLE-search on USPatent 4,157,660. It might be helpful to those with curiosity.