I think.....and that always gets me in trouble.....the first D-8's with a CAT blade and CCU would be in about serial # range of 2U1500 to 2U2000. Before then (1H's, 8R's and early 2U's) were mostly equipped with LeTourneau.

I was only a kid back then but "I think" that's right.

Well I guess I'm going to have to give up on this one. Although I have lots of information there is almost nothing that ties down the years except a 1942 brochure showing the 9R rear double drum Cat ccu unit with mention of dozer application but they don't say whose. This would have coincided with early 8R production but that's about as far as I can get. In any event it appears that several of the hardnose/ccu combinations would be correct attachment applications for the early D8's

Hi team,
from my incomplete collection of early Serv. Mags. I have found a Serv. Mag. article August 21 1939 announcing the inclusion of Instruction Sheets for both the single and double drum CC's. I have these also, and Cat P/No (5B8944 lever) is seen in one pic. of the Brake and Clutch Adj. section.

For the HCU's a Serv. Mag. Dec. 05 1949 tells of inclusion of Special Instructions for D2 & D4 'DOZER BLADE Installation. Mention is also made of a Salesgram April 25 1949 announcing Hydraulic Bulldozer attachment groups for certain machines. This same issue also covers the availability and fitting of pre-formed service plates to the faces of 7A&S and 8A&S blades.
Serv. Mag. dec. 16 1949 covers an article on SLUGGISH HYDRAULIC ACTION D6 D7 and D8 ' Dozer.

I guess these articles only serve to narrow down the release dates of the said attachments. Salesgrams would no doubt tie it down for sure, anyone got any from these eras ?.
Also a list of Instruction Books, available (Oct 15 1949), lists Special Instructions for Installation of Hydraulic Control and Support Group on Early D2 and R2 Tractors :- Form No 12669.

An interesting aside is a scan of a page from Fifty Years on Tracks.
Cheers,
Eddie B.

Seeing how we are getting into CCU's here is the brochure on the 9R double and single drum rear units and a picture of the LeTourneau double drum R power control unit. You don't hardly see any 9R units but I believe they were the grand daddy of the 25's and 24's and others that followed.

edb,
That first picture must be of a LeTourneau unit as I believe they were big on the cone clutches.

Hi OM,
I thought the same thing, BUT, this is the unit I can read a Cat P/No on the lever of !!
The Instruction is a Cat document with Form No 5291 and Form No 5681 covers the single drum unit.
Cheers,
Eddie B.

Hmmm...is there a model # or serial number for either the double drum or single drum unit?

Sorry OM no clues given in the Instructions as to the above. The 1939 & 1942 models are vastly different by the pix. The 1939 D/Drum unit is bevel pinion drive and the 1942 is worm drive. Also the 1939 S/Drum unit is planetary drive. Probably just a case of Cat. buying into another companies product line and modifying it to suit their own needs.
Attached are :- front of D/Drum inst. sheet, pic. of the unit in question, and copy of Specs of Former Models sheet on CCU's, dated March 01 1954 Number 11. I do note that the S/Drum unit does not appear in the FMSS.
Maybe it is the 9R unit as the instruction says for D8,7&6. Although 1E numbers are usually for pre or first production run models of all sorts of equipment !! I think I'm getting more confused than enough, anyway how else can we sort this out so far down the track? with the limited resources we have available, if you and I and others had'nt saved what we did there would be even less to go by.
Cheers OM, I guess you can chew this over for further comment.
Eddie B.

Hi, Folks,
Cat and Letourneau ended their joint marketing agreement in 1944 and Cat started producing its own straight dozer blades and PCU's in 1945 and introduced angle blades in 1946.

So, I'd say at a guess that the first D8's to be fitted with Cat blades and PCU's ex factory would have been the last of the 8R's or maybe even the first of the 2U's.

This is not to say that they weren't making hard noses for the earlier tractors prior to that, only that LeTourneau blades and PCU's would have been fitted to the earlier models if fitted ex factory.

Hope this helps - probably not much.

I have an original parts book for the #23 1E2501-up unit. It is dated 1947 and looks much like the later #25.
Getting back to the 1942 9R CCU and guessing as Deas suggests I would think Cat did not wait until their agreement with LeTourneau was caput before venturing into there own design so I have a feeling the 9R was around at least a couple of years before the split. Unfortunately the parts manual I have for the 9R is a 1953 reprint so no help there. The 9R had a lot of conversion groups (attached) but no info on whose blade it was operating.

Hi OM,
just found this OMI, the 23 & 25 CCU's are look alikes as you noted. The 25 fits the D8,7&6,and the 23 fits the D7&6, both with the correct adaptors as per your list. Print date for this OMI is 6-52. Form No 10922-5.
Cheers,
Eddie B.