Speedometer Drive

[john!]

Ok, I asked this question on the big forum, but didn't get an answer there yet, but I figured I would ask here as well.

My old gearbox was getting very noisy (diff too). Knowing this I had a second hand box sitting ready to go in. After it was installed we discovered that there was no speedo drive on the mainshaft.

A look in the enthusiasts manual shows the worm drive goes over the mainshaft, with a couple of snap rings and a ball bearing to locate it.

The question is whether it is possible to replace it with the box still in the car, by just removing the extension housing. The book is not clear on whether this can be done, as it only details the teardown and rebuild procedure.

Is it an especially fiddly job? Is it just as easy to drop the box? (The diff is being removed anyway) What happens with the shift mechanism? Is it necessary to replace the seal on the output shaft?

Any and all help appreciated.


john