Thread: Range Rover diesel, what gearbox?

Hi, I helped a mate earlier this year transplant a VM diesel and VC centre diff manual transmission ex a 1988 Rangie classic into his ailing 1985 Landrover County that was originally a V8. I know you will be thinking that was a lame thing to do but in reality it has been a real success as far as he is concerned, it made a truck that was pretty well out of the question to run with a sick and thirsty V8 into a reliable run about that you can afford to run that has useable on road performance, (read old guys performance), it has to date been both reliable and ok to drive covering some 20,000 k's since the conversion.
Recently it has developed a noise in the indirect gears, particularly 2nd, 3rd, and 5th, it sounds like a bearing slight clonking when under load and on over-run, we have today removed the transmission and began an investigative journey into the main gearbox, have found no shrapnel in the oil or anywhere we have looked inside, the mainshaft and front layshaft taper rollers are perfect, we still have to get into the main guts of the box on Monday.
We only have a Landrover County workshop manual and are not entirely sure which box we are dealing with, thinking maybe LT77, but I thought they were an aluminium main case, this one is a cast iron jobbie.
So primarily two questions, 1/ What was the standard 5 speed manual gearbox fitted to a 1988 Range Rover Diesel, we know it has the Borg Warner viscous coupling transfer/centre diff.
2/ What in anyone's opinion may be a possible source of the noise, are these boxes prone to any particular areas of bearing, shaft, gears failure ?
An answer to question 2 may get us straight to the problem, thanks.

Hey thanks for the replies, we just happen to have a section in the Landrover County manual on the LT77 gearbox. Today we dismantled the 'box and found what we think may have been causing the noise, all the bearings are a bit shabby but no more than I'd say fair wear and tear for 200K and would not cause what we were hearing in the indirect gears. What we found though was that the rear layshaft, cluster gear roller bearing, whatever you will call it, the outer race, cup has been turning in the support plate and had worn the bore and face sufficiently to allow a reasonable amount of end and radial play.
The manual recommends zero pre-load to plus .001" float, this one has about plus .010", which with the taper roller equates to a fair amount of radial movement.
Not sure what we can do to cure the wear and fix the 'box because I'm sure you cannot simply buy another support plate as I reckon the whole box and cast housing is machined as a set, may look at bore and sleeve or some such.
It mentions a change in this particular bearing from suffix "F" boxes, so it seems this may be a weak spot in the LT77, as it happens this box is an "F" suffix so I'm not sure where that leaves us.
My mate has ordered all the bearings, seals, gaskets etc this afternoon via internet from Melbourne, seeing as we are right up on the Cape it will be a couple of weeks delivery no doubt, that will give us time to work out how to attack the support plate problem, happy days ahead.