sorry to hear you had bad luck with the old gearbox probaly split a gear like i did 2 xmas ago and that was a cts stage 2 i was on m25 doing 65 mph went to over take a car and bang but car still had drive untill i went onto hard shoulder and selected neutral had to pull away in 2nd to get off motorway then just as i got off the m-way it went cap-put then the AA done the rest of the trip
got it back to cts and was found to be a split in half first gear
and now driving another erst with a whinney box when cold but not for long
hope you can get it sorted soon
mark2