Here is the part number off of my speedometer 123 542 85
It is the 85 MPH one, that is matched to the 3.07 gearing.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

Ah, so there must have been 77-82 W123s with different gearing that got the 115 speedos? dastardly business!! Oh well, I guess I've got an extra speedo for a car I don't have

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Eric, CPO, Submarines, retired.
Here's a sig line...
Mine: '68 Corvette LS1/4L65E, 83 240D, 2000 GMC 4x4, 08 FLSTC Anniv
Hers: '72 Corvette 454/4spd, '99 MB SLK, '93 Metro vert, 78 240D, '92 Silverado, '65 Fjord Rustang, '59 Fjord Fairlane, '17 Slingshot.

Could be from a gasser as well. Thank Nader for the 85 MPH speedometers.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D

Yeh I did some more searching (I love the forums!), and even the face part number doesn't always mean the gearing will be correct. There is a W followed by a four digit number supposed to be stamped on the back that gives the number of cable revolutions per minute at 60mph.

So I supposed I could be stuck with a diesel non-turbo, a gasser, a variety of choices.

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Eric, CPO, Submarines, retired.
Here's a sig line...
Mine: '68 Corvette LS1/4L65E, 83 240D, 2000 GMC 4x4, 08 FLSTC Anniv
Hers: '72 Corvette 454/4spd, '99 MB SLK, '93 Metro vert, 78 240D, '92 Silverado, '65 Fjord Rustang, '59 Fjord Fairlane, '17 Slingshot.

Its a diesel non turbo speedo pre 1980's....my 1978 has the exact same one.....when you get it, there should be a manufactured date stamped on the back...

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So, a 3.46 ratio then vice a 3.07. Now I have to wonder what that =s in speedo error...

<<>> 5/79 date code. W code is 1.33

__________________
Eric, CPO, Submarines, retired.
Here's a sig line...
Mine: '68 Corvette LS1/4L65E, 83 240D, 2000 GMC 4x4, 08 FLSTC Anniv
Hers: '72 Corvette 454/4spd, '99 MB SLK, '93 Metro vert, 78 240D, '92 Silverado, '65 Fjord Rustang, '59 Fjord Fairlane, '17 Slingshot.

Don't even ask me what my rest end ratio is the speedo will still work but it will be a little off....I remember my 300d speedo was 85 and I couldn't find an 85mph speedo, so I installed a 120 speedo...it worked but was like 5 miles off...

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Doing some more searching from folks that did rear end swaps (after engine swaps), it looks like I'd be about 12% off, but that's really bistro maths since even my stock unit was 8% off.

We'll see what it does.

__________________
Eric, CPO, Submarines, retired.
Here's a sig line...
Mine: '68 Corvette LS1/4L65E, 83 240D, 2000 GMC 4x4, 08 FLSTC Anniv
Hers: '72 Corvette 454/4spd, '99 MB SLK, '93 Metro vert, 78 240D, '92 Silverado, '65 Fjord Rustang, '59 Fjord Fairlane, '17 Slingshot.

Well worse case, it will mean you will have to buy a 1979 300d to use it in

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