Someone emailed this to me. I'm not sure on the answer. They would fit wouldn't they ?
I will link him to this thread.
I have a 2.0 J reg Astra Gsi 16v and have shafted the gearbox, I have an H reg 1.6 cavalier at my disposal and was going to use the gearbox from that as a temporary fix until I can afford to recondition my box, would you have any experience in this, do you reckon the gearbox would go in. I’ve heard that the splines may be different sizes for a 2 litre and a 1.6.