Post photos

 

 

 

Looks like it is a ZF 6-speed from a petrol car, since you have the same part number. The one linked is from a donor car 530i.

 

The sticker says Getrag. The GS6-37BZ-THEG in the 03/2003-on 330i was made by ZF.....

 

It is a 6 speed. My main concern is that it could be a much cheaper diesel box. I would have thought ZF would have made the markings clear. The numbers relate to bz or dz.

 

That's labeled as a Getrag, not a ZF. Getrag and ZF are different companies.

 

That transmission looks identical to the petrol engine zf 6speed I just installed.

 

Is there any physical difference between the diesel 6 speed and the petrol? I know it’s a gs637 (bz or dz). How do you tell it’s a Theg or Thea? I would have thought zf would have made it more obvious. Just wanted some confirmation before doing the manual swap.

 

There were several variations of this model gearbox, different ratios for z4/330/diesel/petrol with codes bz (Thea/Theg/TjegTjee/Tjes)
and gs637dz, which were for the diesel.

 

Measure how many turns come out of the output shaft for every turn of the input shaft, in each gear. Then look up the ratios- they are out there for each model. But don't get busy and forget to come back and tell us here whether you got the right animal, or not!

BTW: Did you get it from Europe/US? It looks a bit 'salty'.

 

I just stumbled across this thread and thought that I'd add some clarity.
Getrag built GS6-37-BZs under contract, and were also contracted for reman work, but the trans is still a ZF design and as such still a BZ, as in ZF, which is what the last letter in the code indicates.