Well Bill, I tried. Without the IH pn or parts manual for that truck there's not much to go on. Using a casting number is never a sure fire way to find wheel or master cylinders,in many cases all it does is ID the casting itself which can be bored to different sizes and/or have different ports sizes.
I did try the book for the K/KB and by the illustration (K-4&5) it may be the same MC(?). Bad thing is,the page with the pn for a complete MC is not there. I tried a few aftermarket online catalog's for either but only found rebuild kits,1 for a K5 with a hydro-vac and one without. Both numbers rang a bell so I checked a list I've compiled and found both. The app. I noted for one is the R-130 w/hydro-vac and the illustration shows 3 side mounting holes,so it's a strong possibility it's the same MC. This sent me back to the illustration's in the K book and the R book to match the internal pn's,which match perfectly. That raises the probability it's the same as yours greatly.
I say that because the MC used on lighter trucks was used from the D's,K's all the way to the 50's S-series,although that one has only 2 side mounting holes.
Now more bad news, I have searched for at least a year for an aftermarket pn for the one MC and there's just doesn't seem to be one.
That's not really a big issue though,you can rebuild yours as long as the bore is good. If not the only recourse I'm aware of is having it sleeved.
So here's the likely kit pn's;
With 1-1/4" bore
121400H IH
TM3613 Dorman 1
MK1 Raybestos
MK3613 Wagner
With 1-1/2" bore
121401HB IH
MK39 Raybestos
MK3622 Wagner
Here's link's for 2 reputable sleeving vendors just in case.
http://www.karpspowerbrake.com/http://www.whitepost.com/
12 yrs.exp. in IH dealer parts dept.
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