The tires were the biggest problem on the 675 because it was so heavy. I used to have a brochure on the Michigan C series loaders. What's interesting is that it listed the 675C model as the offering the biggest bite on wheels with buckets up to 36 cubic yards(for coal loading) but 24 yd was standard. 16 675's are listed as being built but that's a deceiving number. 2 675B's were bought back by Clark and rebuilt and sold as the C models. The prototype used 2 GM engines but had a lot of problems so they switched to 2 Cummins engines. I knew a guy that bought a 175B new and he said you couldn't hurt it! He also had a 75B and it wasn't as strong but he probably tried to do the same work with it as the 175. Michigan's are known as one of the best loaders ever made. Those old videos are fantastic! As far as the welding, almost all of it designed for fillet welds so it doesn't need as much prep. I would also bet a lot of the steel is thicker to not only give rigidity but also give a good safety/abuse factor without needing to use 3" fillet welds. I would think there was some preheating required and the video showed them using a hand held sub-arc gun with the flux pouring over the weld. The safety police would have had a field day there, welding without gloves, no safety glasses, etc. I'd like to see how they build/form the huge buckets.
The B models were the production models with Cummins engines. Possibly to renew interest in the 675 is why Clark bought a couple back and added similar refinements and improvements to them as the smaller C series loaders. I would think with all the development costs, the 675 was a big money loser for Clark, although from watching the old Clark videos, the 475 and smaller loaders were a great success. Some have speculated that the 675 may have been ahead of its time.
