In my 122 with J type OD, I got all prepared to do this. Got a factory tunnel (new) piece 2 years ago from a fellow in LA for $60. Have the 1800 shifter/cover. I even marked out the line on the tunnel in the car. But I have not done it yet, mostly because I live in the northeast (NYC) where it can get really cold - +1º this morning, and am loathe to give up the heat bladder to the rear, and haven't figured out a clean way to dress the whole deal after it's installed. I don't have a factory front floor mat, and the bladder looks great with it's nubby naugahide looking surface, sans mat. I admit that these are not great reasons. I have a great, tight M40 cover and shifting is crisp, but some wear in the trans - I think it's the roller bearings between the input and mainshaft, allow the trans to drop out of 3rd when I back off the gas under load, and I think part of it is the weight of the long shifter. Methinks the 140 cover would be the ticket, as Pete says, though I am not familiar with the varieties he mentions. Seems like there should plenty of them around. Anybody know of the specific length differences?