Authenticity: Gauges
There are many different styles of instrument gauges fitted to T34s over the years. But there are two sizes of speedometers, two colors of needles, and two colors of center knobs. The early years (1962-64) had small speedos, red needles, & bronze center knobs. The middle years (1965-66) had large speedos, white needles, & bronze center knobs. And the late years (1967-69) had large speedos, white needles, & silver center knobs. There were also MPH and KPH speedometers with different numbering schemes. Take a look at the pics for clarification.
SMALL DIAMETER SPEEDOMETERS:

Early-1962 KPH 150kph amber needle & bronze knob

1962-63 MPH 90mph red needles & bronze knobs

1962-63 KPH 150kph red needle & bronze knob

1964 MPH 100mph red needle & bronze knob

1964 KPH 160kph red needle & bronze knob

LARGE DIAMETER SPEEDOMETERS:

1965-66 MPH White needles & bronze knobs Typical 10/30/50/70/100 increments

Unique 1965 White needle & bronze knob With tenths/mile odometer!

1965-66 unique White needles & mixed knobs Strange 100mph with 10mph increments!

Late-1966 White needles & mixed knobs Some came with mixed gauges

1967-69 KPH White needle & silver knob Typical 10/30/50/70/100 increments

Late-1969 KPH White needles & silver knobs Unique tenths/km odometer!

TACHOMETERS: Authentic T34 tachometers were VDO and had a notch cut-out of the top-back of the gauge. None were sold through dealerships as accessories. And there are several different versions of reproduction tachometers.

Authentic Early VDO Tach 6000rpm, red needle & bronze knob Back has cut section

Authentic Late VDO Tach 6000rpm, white needle & bronze knob

Repro Tach (Tim Dapper) 7000rpm bronze tach with colored redline area

Repro Tach (Tim Dapper) 7000rpm bronze tach with colored redline area

Repro Tach (Gossen) 6000rpm bronze tach closest to stock

Repro Tach 8000rpm bronze tach 2003 reproduction

Repro Tach (Tim Dapper) 7000rpm silver tach with colored redline