I have to agree with Sasquatch that both tractors have the "forged body pumps" as oppsed to the earlier "Flange type", which started with S/N 2H 3248. As to the shift lever cage, that was effective with S/N 2H2866, so they both have to be later than S/N 2H 3248, which included the heat indicator and the round top air cleaner. I would like to consider obtaining the complete generator and drive group. Bill Walter 816 891 8654

on further inspection you are correct on the injection pump.

Here is some additional information.

The Inside Unit with the D6 badge has both serial number plates intact on the chassis rear and on the engine. Both tags indicate 2H6753.

The Outside Unit with the RD6 badges only has the rear chassis serial number plate intact. The engine serial number plate is missing. The chassis tag indicates 2H4360SP.

I would assume that these are both officially D6 machines. So Sasquatch is likely correct in that the radiator may have been swapped out of the one with the RD6 badges or it was old stock being used up.

Also per u-joint's comment on the badges, the RD6 badges appear to be brass and look brand new under the paint. The D6 badge on the inside machine is stamped metal and heavily rusted.

I am assuming that the "SP" indicates something like special purpose or special parts. Possibly because of the generator and/or the earlier style carrier rollers. I am not sure if the rear mounted Gar Wood Hydraulic Unit would warrant the "SP" designation.

Attached are some serial # photos, the brass/bronze RD6 badge and the Gar Wood Hydro Unit SN plate from the outside machine.

I took some measurements for the undercarriage on the Inside Unit for those who are interested. We would appreciate any feedback with regards to the condition of the undercarriage based upon the below information.

Rail measurements were taken by laying a metal rule across the rail and measuring from that edge to the backside of the pad. Three measurements were taken at random on each side.

Left Rail = 3-9/16", 3-5/8", 3-21/32" Left Rail Average = 3.615"
Right Rail = 3-9/16", 3-9/16", 3-17/32" Right Rail Average = 3.552"

For D6 rails, I found the following information on-line. Not sure how accurate it is.
Normal Height = 3-25/32"
Suggested Maximum Wear Limit = 3-5/8" (3.625")
Maximum Allowable Wear = 3-1/2"

So the rails appear to be beyond the suggested maximum wear limit but not at the maximum allowable wear limit. I am wondering if we are through the hardened material and possibly into the softer material. Dad is looking for his old maintenance manuals to see if there is anything in them that would validate the above.

Grouser Measurements were taken by laying a metal rule across two adjacent pads that were supported from underneath in a linear position and measuring from the bottom edge of the rule to the top of the track pad.

Left Grouser = 7/8", 3/4", 13/16" Left Grouser Average = 0.94"
Right Grouser = 1-1/8", 1-7/32", 1-3/16" Right Grouser Average = 1.18"

I wasn't able to find anything on-line related to grouser wear.

Pin and Link measurements were taken for 4 links with slack removed measuring from pin center to pin center.

Left Pins/Links = 27.4" (44% remaining) Note: Pins not turned.
Right Pins/Links = 27.1" (86% remaining) Note: Pins not turned.

For D6 pins and links, I found the following information which the above % remaining #s are calculated from.
% Worn Inches
0 27.00
25 27.17
50 27.34
75 27.51
100 27.71

For the sprockets, I am not sure how to take wear measurements for them. So we measured by layng the rule across two adjacent sprocket teeth and measuring from the center point to the bottom of the curve where the pin rides.

Left sprocket = 1-1/4"
Right sprocket = 1-1/32" Note: Sprocket teeth points have been welded up by my Dad at some point in the past as this sprocket is very worn.

I thought it was interesting that the pin and link meaurements indicate a lot of life left in them and the pictures indicate that as well as the right side pins hardly seem worn at all (88% remaining) vs the left pins showing some wear but still not looking to bad. On the other hand the rails are well worn according to the measurements but I couldn't really tell from looking at them how bad was the wear. I think I am going to re-meaure them to see if I did something wrong the first time.

Attached are some pictures of the pins, rails and sprockets for the inside unit.

Crine - We would need link and shoe part numbers before anyone can offer advice on the undercarriage condition.
There have numerous changes/improvements to undercarriage design over the decades, and the tracks are probably not original, anyway.

Regards, Ron.

That undercarriage is wore out.
Either 6.75" pitch chain had link ht 100% worn at 3.48" or 3.61"
The 5 pin 4 link measurement 26.98" new is 100% worn at 27.4"

Gee, I don't know OM - that carrier roller in pic 2 looks like its good for another 500 hrs!
You ain't never been a contractor, have you??

Ya, I saw that, kinda made me cringe.
Nope, never had to scrape bottom to survive in the contractor world.

It's amazing how long a block of wood lasts in place of a carrier roller.

Hey c'mon Wombat, curious minds need to know - is there a preferred timber variety and grain?
Does Mountain Ash perform better than Stringybark, and is it crucial as to which way the grain is aligned?