My RS, build date 4/73, came with 250 km/hr speedometer. According the RS bible of Dr. Konradsheim it should be a 300 km/hr VDO. On the outside are a couple of numbers stamped and the date of manufacturing, 11.72.

Did Porsche stamped the date in it in order to correspond with the build date of the car, or was it VDO and how close should they match ?
The following numbers are on my 250 km/hr speedo:
part. no. 911.641.501.00,
26/30/1 and W=0.5 T. What do they mean, I guess 0.5 has something to do with the calibration and/or tire size.

Is it correct that VDO made different gauges for different tire sizes, like the 50 and 70 series tires ?

Does anybody know the part. no's for the 300 km/hr speedo's for 50 series or 70 series tires, and if they are still available.
How about 60 series.....