Thread: Series 3 gearbox into a Series 1

Originally Posted by QRS40

If you are needing to replace the engine either way, originality won’t necessarily be as relevant will it?

It does not have the correct engine in it (siamese) and I will put the correct spreadbore engine in it.

a SII box will work and a SIII box and be back fitted to a SII box. BUT...

it has to be a late II box and an early III box AND you have to do some custom bearing selection AND some machining BUT..

yes, you can effectively make a SIII box fit into an SI if you have the gear, the verniers and the patients with a good bearing guy.

The SI engine will pull the 3.54's but its not going to enjoy 4th or work well off road. 4.11's is about as good as you're going to get and you have to be on the SI small rubber...