On a new machine in the 1950’s how much track adjustment was there in inches ?  thanks 

It has been a long time, since I had threaded adjuster apart. But would guess between 6 and 8 inches of threads. And of course you need a better than a inch of threads in the casting , so inches maybe could be a bit less.

You can get a feel for how much is left by looking at the ware plates on top of track frame the idler slides on. There is about a inch in front that was not meant to be used. Not that most don't push that at the end of the tracks life. To get just another few hours out of the junk tracks.

I have a machine that has 7 inches between idler clamp face and stationary plate face. was asking about how much space was there when the machine was new. thanks

Never seen a spec for new but here's the adjustment specs.
 

Right from new there would need to be some allowace for slackening the track to facilitate fitting the joiner pin so possibly an inch or two there.

Does anyone know what size wrench that would be on a d2 4u series. I have a 2 3/4 and it’s to big. Thanks. Mike Hudson

I love the white lab coats. TractorDon, you need to ditch your Carhartts and go back to your white coveralls. JM

According to the hour meter on this 1950 d6 9u i own it’s showing 451. (right) only 3 digits. are these meters foolproof or totally incorrect?
it was supposed to be a one owner tractor. thanks

Should be easy to tell 10,500 hours from 500. Look at the tracks, linkages, deck plates, and brake petals. I have no real trust of Cat hour meters. I cannot recall a working one hardly.

D2 track wrench is 2-1/4” 2F5131.