Just finishing up a restored 12 steering column, where some previous enthusiast had cut the brass control rod keepers to extract the rods. When the casting keepers were spread to release the rods, the brittle thin wall brass fractured, so these pockets had to be welded and machined, to recover the part. I've heard folks here endorse this practise, and I have to say, I think this is just plain reckless. These rods are worth nothing, and they can be easily sawn above the deck, then threaded to put back together. The brass lower planetary castings are premium items, especially when the planetary housing is in good shape, and remains reliably fastened to the low casting. No rational need to destroy these rare parts...their complexity and low volumes, nobody will ever repro these.
Is it or was it a practise?
not that I've had many apart, but the few I have are as you described, even the parts book show them slotted.
I believe the thin keeper fingers were initially cast in an "open" position and were later bent to wrap around the rods upon assembly. As Kerry points out, there would then be a subsequent slot, or slight gap, where the fingers met. Restorers are simply trying to pry back the fingers to the open position to extract the rods. They are not cutting anything. However, the thin fingers do usually break when attempting this. I guess you could just cut the original rods and sacrifice them but I don't like purposely destroying ANY original pieces if I can help it.
Early, two piece steering gear cases and control rods are completely different animals from the later style that appeared for the '15 model. Although, there are cases of "carry-over" insertion of the early, flattened out control levers as opposed to the "mouse ear" style on early '15 cars. The lower early riveted gear case piece had slots to allow the control rods to be inserted prior to being riveted together to the upper case. There are no splits in the lower case to insert and hold the rods captive - they are a full circle and the control rod was inserted through the full circle, past the slots on both sides of the lower gear case THEN the two gear case pieces were riveted.
This rig on my project was as per the early photos (thx Steve). No question this particular unit had been bastardized to avoid option A:taking the 2 planetary halves apart, or option B:cutting the rods as I mentioned. In addition to others, I had a restorer known to this Forum, recommend this hack tactic to me. These early pieces are simply too rare to trash with rash methods like this. I was fortunately able to save the piece, but it was a tedious and time consuming effort.
Kerry: No question that the later assemblies had the pre-split arrangement. The splits on those are nice and neat, but are also fragile castings where I doubt they were intended to be taken back apart. I think it certain that the later technique was created to expedite the steering gear assembly process.