The Stovebolt Site Forums The Shop Area Driveline r10h-1 and r10h-1a , is there a diffrence

is there a diffidence between the two? thanks for any input!

Hy drew_vigil, other than one having an "a" that the other one does not have, I don't know. What exactly are you asking about? What do the alpha-numeric numbers represent?

BW overdrive.

I have not seen the -1a casting but it must have something to do with the series. It's still a GM. Just when I thought I knew almost everything about these units I picked up a Chevy/BW OD with a R10K-1 casting #. It has a 4 bolt side cover, a 1964 date code with the rear mount pad.
I'm going to tear it down and see if anything is different.
Fred

The BW OD units are all very similar. I have seen parts from a Ford BW used in other OD units. If its working, I sure wouldn't tear it down to see what the difference is. If it is a 4 bolt cover, the front is a Muncie. I don't see what difference it makes what the casting number is on the OD unit.

I HAVE ONE OF EACH INFRONT OF ME, THE INPUT SHAFT ON THE 1A DOSENT TAPER DOWN, BEFORE THE RETAINER LIKE THE R10H-1. tHAT WONT BE A PROBLEM AT ALL WILL IT?

Many of the internal parts interchange on the BW units such as blocker rings, planetary units and roller clutches. The parts that do not interchange are specific to the OEM such as housings, mainshafts, etc. The R-10K unit that I have is here for repair. Initial inspection reveals that it is the same as every other GM OD I have rebuilt over the last 40+ years. I had not seen the K designator before or not paid attention to it.
The solid shaft on the clutch gear is probably a Warner replacement part.
There is a GM oddity out there that was used in 64-65 in a Chevelle. It uses the same BW unit but the mainshaft and all the internal gears have a different pitch. None of these parts will interchange with the conventional SM318/319 gears.
Fred

It turns out that the OD gear box with the R-10K-1 designator is somewhat different. It has a shorter spedo housing & gear, casting for a rear mount, and a fine spline output shaft (like a TH350 or powerglide). The main differences are the internal gears in the trans itself. It appears to be one of these odd units as none of the regular SM318 gears will interchange.
It could be expensive to rebuild as it needs a cluster gear & a L-R slider. I usually pick up regular 3 speeds to use for parts but they won't work for this one.
Fred