It's all fun and games until the wheels come off...
Back in the day (circa 79 I believe) the options would have been 45 Vibra Shank , 645 Vibra Chisel and 55 Chisel Plow... so it's probably more similar to your vibra tiller than a vibra shank.That has the five ranks, what series is that? Looks something like the frame I have on my 4700 vibra tiller, except yours is the older style. My rockshaft brackets are heavier and greasable as well.
Sounds and looks like it yes, mine is a bit newer. Was thinking about this, and one thing you could do if you can get the rockshaft straight enough, is make extended bearings for it, as to spread out over a larger contact area, that would help take some of the flex out of the shaft where it has been weakened by getting bent.The main load is carried by the cylinders anyway. In this part of the country, some of those older IH machines get given away because the shanks and trips are wore out. My 4700 is getting there too. Some of my trips are wore to where I can move the shovel a couple inches sideways. Its 6.75 spacing IIRC and I use 9 or 11 inch so they need to be wore a bit before any misses. Actually don't even use it that much anymore, always have a chisel plow now with sweeps and they handle the rocks and trash better.Back in the day (circa 79 I believe) the options would have been 45 Vibra Shank , 645 Vibra Chisel and 55 Chisel Plow... so it's probably more similar to your vibra tiller than a vibra shank.
I have a 41' frame sitting with no shanks on it.This is vibra chisel, not vibra shank... heavier. I share your concerns, but changing out that tube isn't an option unless I find an identical parts machine, and they are few and far between. I'm considering an internal pipe, but the weld seam on the old one prevents a good fit.