I did see that one Mike but it's not a long track frame unfortunately and the attachment holes etc. don't line up. I do have a parts tractor and have been over its frames to check the feasibility. I have new D3 rollers now so that's what's going on it. I assessed the old rollers and they're a total mess so not even worth rebuilding, maybe one or two of them. The parts tractor has rebuildable shells

I was able to remove the rollers, carrier and stand, and recoil spring guard loop tonight, however to do so, I had to cut the side out of the roller mounts because no amount of heat would loosen the hold that both the roller mount and the thread through the frame had on the bolts, even with the new 1400ftlb Milwaukee rattler. All I ended up doing was breaking the bolt heads off. This tractor has, and is continuing, to fight me every step of the way. So now I have some fun time ahead removing the broken bolts. Some of the holes had nuts and bolts and the holes are wallowed out.
However the good news is that I think I just need to replace the channel extension where the idlers mount. They're splayed out and severely worn but the rest of the frame from the first roller back is straight, so it'll be an easier fix, but still fairly time-intensive. I will need to fabricate new carrier stands because they're rust-wasted and don't suit the D3 carrier mounting requirements.

The bolts I need to remove are the four that hold the carrier roller stand and the recoil spring guard. You're right though, I don't really need to remove the roller retaining bolts, just grind them off flat. The previous owner torched the whole threaded area out in a couple of places, so I want to weld in some replacement stock to help prevent standing moisture from accelerating the rust in the bottom flange.
What I have figured out is that outside of those things, I can replace just the parts of the channel that extend forward for the idler - the rest should hold together for the foreseeable future. A couple of places I'll cut out some wasting and replace with some new steel. That should save me a bunch of time and expense. Apart from making them robust again, my other main focus is to try to get all the rollers and the idler lined up with each other, and in the center of the frames horizontally and with the correct lower rolling surface height. Scott's large idlers will be at the same rolling height as the idlers since this machine has a blade.

 

I'd be very interested in seeing your templates if you're willing to share restore49? Did you make a new pivot shaft tube? The one item I was trying to figure out was the correct channel size because on mine, while the base is a standard 5", the top leg is 2" and the bottom is about 2 3/4 best I can tell. I guess the bottom is not critical because the idler mount only needs the top leg - what did you end up using?
While I'd like new frames to put on now instead of messing around with these ones, these can be patched, which of course would give me time to build a new pair of frames while still enabling me to use the machine while that happens.