gearbox shift problem
 

gearbox seems to only choose 3rd 4th and 5th gears, whats likely reason

First guess would be misadjusted coupler at the front of the trans (the one under the tunnel plate just behind the seats).
There are several good threads on how to adjust it.
Bob

Right - or the bushings in the coupler are worn too much. Same place to look. Go on the 911 forum for 915 advice, of which there is plenty. Look for "coupler."

HI daveg74
it is a 915 box 1974??? if so check the bushes under the gear lever also, for wear, as a small amount under there is a large amount in the box, is there any noise from the box when shifting?

regards mike

gearbox shift issue
 

yeh mbe engineering there is no noise in gearbox. obviously i can`t drive the car like it is but sounds solid.
it is a 915 gearbox. the gearstick does feel floppy. not tight shifts

thanks bob will look

thanks all for advice.

Take a look at the following 2 links:

Pelican Technical Article: Shifting Improvements - 911 (1965-86) - 930 Turbo (1975-86)

Pelican Technical Article: 911 Shifting Improvements

This should help you isolate the issue to some degree.