I've just bought my 3rd grande and its the 1.9 diesel m jet. I bought it with a noisy gearbox
Now the car drives but sounds like the engine is scraping off the floor

Any ideas on a fix for this or maybe a different gearbox I could use.

Or is anyone breaking a 1.9 and has a good gearbox

It's a common fault with the GM M32 gearbox the diff bearings and bearings on top of 6th are starved of oil because the gearbox end case restricts oil flow. There's only 2 ways to 100% get rid of the problem. 1st one being buying a reconditioned gearbox with uprated bearings and larger end case, or get you local gearbox rebuilders to recondition your gearbox. (it's easy to find Vauxhall VXR Specialist who specialise in the gearbox as they're in everything VXR). It should cost between £450-£550 to get either option sorted, or alternatively you could buy an original M32 gearbox for £250 and risk the diff bearings, it depends on how long you plan on keeping the car.

The Alfa guys - Autolusso in particular who are a bit presence on Alfaowner - used to recommend over-filling the box with oil, can't remember by how much now but info readily available. This helped keep the bearings on the end of 6th wet preventing the issue.

But Nathan is right, it's the M32's significant weakness and incredibly well documented just how poor and prone they are to it.

It's a shame as the previous box - not sure exactly what it was - that they used to fit to the 1.9s was bullet proof.