[Proj] Datum-Shift WGS84 to Arc1960 not working propberly

[Micha Neubauer]

Dear List,

I am in Tanzania and I want to transform some location data which I was given 
in WGS84 to the locally used Arc1960 Datum.

So I do:
$ cs2cs +proj=utm +zone=37 +south +ellps=WGS84 +datum=WGS84 +units=m +no_defs 
+to +proj=utm +zone=37 +south +ellps=clrk80 +units=m +no_defs

But it is giving me a different result than my colleague gets using the garmin 
software and I think his results are correct and mine aren't

For the UTM WGS84 Point:
332368 9613672

Using the above command I get for UTM / Arc1960:
332365.02   9613707.55 0.00

And Garmin (which is probably correct) gives for UTM / Arc1960:
332274 9613972

Does anybody know what I am doing wrong? Do I need any more parameters for the 
datum-shift? And where can I get them?
I have the Proj4 WKT string from http://spatialreference.org.

Thanks very much in advance
micha


		
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