I've looked all over for this and the only thing I found was in the shop manual. They look like they're on the left side. On my axle halves it looks like they should be on the right because there are undercuts made for a socket wrench.
So, do the nuts go on the right or left side?
They are usually on the side opposite the ring gear.
You probably already know this but incase someone else reads it later I thought I would add a note about one of the common mistakes made in rebuilding the rear axle for the first time. If someone rebuilds it incorrectly they will almost never do that one again. The read axle can be assembled with the ring gear on either side of the small pinion. It fits and goes together just fine with no obvious problems on either side of the pinion. But if it is on the left side of the pinion (driver’s side for normal USA cars) the car has the standard 2 speeds forward and one reverse. If it is installed on the wrong side – it now has 2 speeds in reverse and only one very slow speed forward. And in the second case, the person gains the experience of opening the rear axle up one more time. The good news – all the bolts are already cleaned up and will come apart easily.
I looked for photo showing the rear axle halves and which side the nut went on – but I was not able to find one yet. I’ll check some more later and post one if I can find a good one. There are several of restored cars, but I have not found one of a car on the assembly line that shows that detail.
Hap l9l5 cut off
Fig. 322 at page 142 in Ford's service manual shows disassembly/assembly of those bolts. It's a bit unclear in the picture, but looks like the nuts are on the RH side like Jack says. But a left handed operator on the assembly line may have placed them on the left side on some cars, who knows ;)
Bob McDaniel's recently posted (probably untouched) 1913 has the nuts on the right. Looking at rear axles here, four of mine (pre-26) also have the nuts on the right. Of three 26-27 axles, one has them on the right. I can't guarantee that none of these have ever been split since they left the factory, but I suspect that's the case with most of them.
Jack posted it best...'usually opposite the ring gear'.
IMO have always found the nuts on the right housing, the drain hole side. Have rebuilt many originals, and the nuts are always on the right for me.
Here is Ford fact (Owners Manual picture)
...and contemporary article in Ford Owner showing the nut side detail clearly.
...and Service Manual photo
But the best is perhaps the line drawing made back in the day by illustrators, who most times make accurate representations of the factory parts, so real owners would not see a bad drawing or incorrect portrays, that reflect on workmanship or knowledge.
Note the illustrator has the nuts on the right
Imitation is the sincerest form of flattery!
And original T's, likely untouched, so the manner of fastening the rear axle pumpkin.
Very original 1915.
My barn fresh '23
Dan, I had seen the shop manual (third image) picture. My sight is improving but still not so good as of yet and I couldn't distinguish between a bolt head and a nut. I assumed the nut was being wrenched with the L-handled socket, but it's the other way around - they're turning the bolt, not the nut. I assumed since most people are right handed that it would be easier to install and tighten the nuts on the right side but after I mal-interpreted the shop manual picture, I wanted to confirm.
Hap, that's a very good point to bring up. The pictures posted in my other thread do not show it, but I "borrowed" an idea I saw on the Forum and marked my axle holder accordingly. This alone has been the best way for me to keep things straight in my head when I don't have everything right in front of me and I have to explain something at the machine shop, etc.
This is the pic - whoever posted it please step forward and take a bow!
Thanks all for your responses.