It's been a while now, but I ended up mounting the underslung counterweight to the rear of my 6018 that no longer sports the backhoe which required the counterweight near the front of the tractor. I took Toolslinger's approach and modified it a bit. I removed the counterweight from the mounting arms and made a spacer for the front of the arms that is the same width as the weight. Then I mounted the arms to the tractor as per the factory placement. To the rear of the arms that extend out from the rear of the tractor that originally served as the mounting place for the backhoe, I added a 3/4 inch steel plate that also included 3/4 inch mounting brackets and a rear hitch for a trailer ball or clevis. I then set the counter weight onto the mounted plate, only I put the butt end of it down on the plate (an alternative to Toolslinger's placement). I added 1 inch angle iron on the bottom plate to serve to keep the weight in position, and also used 1 inch square tubing bolted underneath the seat to steady the weight. These brackets are bolted to the weight using some of the original weight mounting holes. I added two 2 inch heavy steel pipes as uprights to carry tools such as a shovel or rake. Another cross piece of angle iron serves as a mounting place for a set of LED lights to provide rear lighting. Later, I added a metal ammo box to carry a log chain, rope, gloves, clevis, etc.
Having the "counter weight" repositioned to the rear of the tractor has made a tremendous difference in the tractor's traction and use of the front-end loader. My thanks to Toolslinger for the idea!